EP0039986A1 - Système transducteur acoustique - Google Patents

Système transducteur acoustique Download PDF

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Publication number
EP0039986A1
EP0039986A1 EP81300378A EP81300378A EP0039986A1 EP 0039986 A1 EP0039986 A1 EP 0039986A1 EP 81300378 A EP81300378 A EP 81300378A EP 81300378 A EP81300378 A EP 81300378A EP 0039986 A1 EP0039986 A1 EP 0039986A1
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EP
European Patent Office
Prior art keywords
vibratable member
sound
zones
acoustic
transducer
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EP81300378A
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German (de)
English (en)
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EP0039986B1 (fr
Inventor
Stanley Panton
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Siemens Canada Ltd
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Federal Industries Industrial Group Inc
Milltronics Ltd
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Priority to AT81300378T priority Critical patent/ATE2981T1/de
Publication of EP0039986A1 publication Critical patent/EP0039986A1/fr
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    • 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

  • This invention relates to acoustic transducer systems, and more particularly the coupling of a tuned transducer element to a low impedance medium in which sound waves are to be propagated to or from the transducer. More particularly, the invention is concerned with transducer systems suitable for example for use in pulse-echo ranging applications in which it is desirable to combine high coupling efficiency and highly directional characteristics with a relatively low transducer "Q".
  • Transducers of the type with which the present application is concerned are utilized for the conversion of acoustic energy into or from another form of energy, usually electrical energy, and depend upon the vibration of a mechanical element of relatively high acoustic impedance being converted into or generated from said other form of energy.
  • the vibration of the mechanical element is coupled to a medium to or from which acoustic energy is to be transmitted or received, this medium typically being air which has a very low acoustic impedance.
  • This coupling determines the efficiency of the system, its frequency response, and the directionality of the propagation of the energy.in the medium.
  • acoustic transducer assembly utilizes an axially deformable cylindrical element such as a piezoelectric crystal held in an open end of a cylindrical support such as a tube. Sound waves emanate from the end, or radiating aperture, of the tube when the outer end surface of the element vibrates in response to an excitation of the element as by electrical stimulation.
  • a transducer assembly is commonly utilized for transmission and/or reception of sound in a gaseous medium, the sound usually being of a high frequency such that the sound wavelength in the medium is smaller than the dimensions of the radiating aperture.
  • the radiation pattern of sound emitted from such a transducer approximates that of a plane circular piston operating within an infinite baffle. It is well known that the directivity of such a transducer is a function of the ratio of the diameter of the radiator to the sound wavelength in the propagating medium, so that a radiator of larger diameter will exhibit a higher degree of directivity than will one of smaller diameter while propagating waves of the same length into the same medium. Thus, for a given directivity, a lower sound frequency requires a larger transducer element.
  • the problem is present irrespectively of whether the sound is radiated from the transducer assembly into the medium or from the medium into the transducer assembly, and is manifested by a substantially reduced coupling and bandwidth of the acoustic energy transferred between the source and the medium.
  • the difference in impedance is enormous, being of the order of 10,000 to one or greater.
  • the essence of the coupling problem is that the low impedance gaseous environment offers very little opposition to the motion of the high impedance piezoelectric crystal so that little work is done by the crystal in imparting motion to the gaseous environment.
  • a well known means whereby the crystal may be made to do more work on, and thereby impart more energy into, a gaseous medium is to arrange for the crystal be stimulated at one of its natural resonant frequencies thereby causing the motion of the crystal surfaces to be greater by a factor of ten or twenty or more times.
  • the same crystal surface area works against the same opposition offered by the gaseous environment but through a much greater distance each time the crystal surface moves through one cycle of its motion. More work is therefore done and more energy is imparted to the gaseous environment for each cycle of motion of the crystal surface.
  • Another well known means whereby the crystal may be made to do more work on, and thereby impart more energy to a gaseous medium is to place an intermediate structure such as a rigid cone or diaphragm, whose frontal dimension is greater than that of the crystal, between the crystal and the gaseous environment.
  • an intermediate structure such as a rigid cone or diaphragm, whose frontal dimension is greater than that of the crystal, between the crystal and the gaseous environment.
  • Such an arrangement suitably constructed according to well known principles results in a greater area (according to the ratio of the frontal area of the cone or diaphragm to that of the crystal) of the gaseous environment being displaced by the motion of the crystal. Accordingly, a larger area moving through the same distance against the same opposition offered by the gaseous environment results in more work being done by the crystal than would be the case if the crystal were operated without benefit of the intermediate structure.
  • the performance of the device can be influenced in various ways, but if a highly directional output is required, only a modest improvement in output can be achieved, since the size of the diaphragm is limited by the necessity for maintaining a coherent wavefront and a gross impedance mismatch remains.
  • a third well known means whereby the vibrating element may be made to do more work on, and thereby impart more energy into a gaseous medium is to place one or more impedance transforming transmission line sections between the crystal and the gaseous environment.
  • This latter method of impedance matching has been fully described in United States Patent No. 3,674,945 issued July 4, 1972 to Hands for "Acoustic Matching System". The operation of this latter method depends upon the-acoustical properties of the matching section or sections which are placed between the high impedance crystal and the low impedance gaseous medium and upon those of the crystal and the gaseous environment themselves.
  • the severity of the impedance mismatch between a piezoelectric crystal and a medium such as air is readily demonstrated.
  • the crystal may have to be driven at such large amplitudes of pulsation that the crystal may fracture, while with the insertion of some form of matching structure between the crystal and the air environment, the same sound power can be transmitted into the air by driving the crystal at substantially reduced amplitudes of pulsation which do not induce crystal fracture.
  • Proposals have been made to match the impedance of a high impedance driving source such as a piezoelectric crystal to a lower impedance environment such as air by the use of an intermediate structure embodying a vibrating plate or disc, but it has not been possible heretofore to achieve such a match without sacrificing directionality and/or bandwidth.
  • an acoustic transducer assembly including a driving element comprising a piezoelectric generator in the form of a disc with a high mass backing element bonded to one face and an acoustic wave transformer bonded to the other.
  • the wave transformer element varies in cross-section in an axial direction, comprising discs of maximum dimension at the generator face and at the radiating face.
  • a highly directional field of sound emission is not a requirement.
  • a main feature of the device is that phase differences across the vibrating disc cause the central lobe of radiation to be suppressed, and cause the side lobes to be enhanced to the point that a major portion of the energy radiated is radiated away at an angle of about 45 degrees to the main axis of the device.
  • transducer systems suitable for pulsed echo-ranging applications in gaseous mediums have been of the type disclosed in U. S. Patent No. 3,674,945, or more simple and inefficient coupling methods have been used, together with some mechanical and/or electric means for damping the vibrating element thus leading to very low efficiencies.
  • a further problem with such systems arises in applications where a substantial range is required. Since absorption of sound energy by gaseous media increases with frequency, longer ranges require not only greater power but lower frequencies, and this means that to obtain the required directionality and power output, larger transducer elements must be used.
  • the piezoelectric materials widely used for such elements are both expensive and massive, and whilst it would be entirely possible to produce a transducer system according to U.S. Patent No. 3,674,945 which will perform satisfactorily at 10 kHz, the mass and cost of such a system would be excessive for normal commercial applications.
  • a broadly tuned directional acoustic transducer system comprising a vibratable member, e.g. a plate, having a radiating surface and a higher order flexural mode resonance at substantially the operating frequency of the system, and a transducer element, of much smaller effective area than the radiating surface of the vibratable member, connected to the vibratable member for excitation of, or response to, said higher order flexural mode resonance, is characterised in that at least alternate antinodal zones of the radiating surface of the vibratable member are coupled to a gaseous propagation medium by means formed of low-loss acoustic propagation material of much lower acoustic impedance than the vibratable member and applied at least to said alternate antinodal zones of the radiating surface thereof in a thickness selected to differentiate at.
  • the vibratable member is axisymmetrically resonant and in presently preferred forms of the invention is in the form of a a disc-shaped plate coupled axially to the transducer element, the axis of the plate and the disc also being the directional axis of the system.
  • the covering low-loss acoustic propagation material is arranged in concentric rings covering adjacent antinodal zones, the thickness of adjacent rings being different so as to produce coherency of radiation in the axial far field.
  • the thickness of material covering alternate zones is zero, i.e. alternate zones are uncovered.
  • the matching into the propagation medium from the covered zones can thus either be made so much better than that from the uncovered zones that substantially no phase cancellation occurs in the axial far field, or sufficient phase shift can be introduced in sound radiated from the covered zones to substantially reduce cancellation.
  • the whole radiating, surface of the vibratable member may be covered by material, of thickness such that there is both phase shift of radiation from alternate zones, and acoustic impedance matching between the vibratable member and the propagation medium, usually air.
  • the covering material need not be uniform, and adjacent zones could be covered by different material, or the material could comprise layers of different materials or have graded properties provided that the desired phase and/or amplitude modification is achieved.
  • the improved coupling of the system to the medium damps the system thus reducing its Q and rendering it capable of use in echo-ranging techniques without external damping.
  • a directional transducer system suitable for transmitting and receiving pulses of sound at a predetermined frequency comprises a pair of annular piezoelectric crystal elements 2 operating mechanically in series in an axial compressive mode, electrical contact with the ends of the ele- nents being made through lugs on conductive brass washers 4.
  • the elements may be of lead zirconate titanate or other suitable piezoelectric material and connected to a winding of a suitable electrical matching transformer 6 (see Figure 3) through which electrical signals are transferred to and from the transducer.
  • the elements 2 and their connection washers 4 are sandwiched between a loading block 8 and a vibratable member 10 having a disc-shaped upper part with a flat upper surface and a lower part of inverted conical configuration. Measured parallel to the axial direction, the member 10 is thicker in a middle or axial portion than at its periphery, and the entire sandwiched assembly is held together by a through bolt 12 and a nut 14.
  • the diameter of the upper part of the plate 10 is much greater than that of the elements 2, and the material and dimensions of the member 10 are selected so that it exhibits a higher order flexural mode resonance, exhibiting in the case under consideration a single nodal circle, at a frequency close to the desired frequency of operation. In this mode of resonance, the zones of the member 10 radially inside and outside the nodal circle are moving in antiphase.
  • a ring 16 of lower density elastic material typically closed-cell polystyrene or other synthetic plastic or rubber foam, or non-foamed resilient synthetic plastic such as polyurethane.
  • the material should be such as to allow propagation of the sound waves with low losses, i.e. it should exhibit low hysteresis as an acoustic propagation medium.
  • the axial thickness of this ring is discussed further below but is such that sound waves passing through it from the member 10 undergo a phase reversal as compared to waves passing through a similar thickness of air. (It is assumed for convenience that the system is operating in air, and this will normally be the case, but it will be understood that the invention is equally applicable to systems operating in other gaseous media.)
  • rings 18 and 20 of low density low hysteresis acoustic propagation material which may be the same as or different to that of the ring 16, are applied, respectively, over the ring 16 and against the member 10 within the nodal circle.
  • These rings have a common axial thickness which is an integral odd number of quarter wavelengths of sound at the operating frequency in the material of the rings so as to provide acoustic impedance transformation between the member 10 and the adjacent air.
  • the vibratable member is of uniform thickness, which both simplifies manufacture and greatly assists in predicting its resonance characteristics, and will be referred to as the plate 10. It is operated in a still higher order flexural resonance mode, with three nodal circles, so that the number of rings 16, l8, 20 is correspondingly increased.
  • An additional loading and driving block 22 is provided to couple the transducer elements to the plate 10.
  • the transducer elements 2 are shown as being four in number, but this will depend on the operating frequency required, the piezoelectric material utilized, and the dimensions of the system.
  • the system is enclosed, except for the radiating surface of the plate 10, in a housing 24 in which it is sealed by peripheral polyurethane seal 26 and a felt seal 28.
  • An air space 30 beneath the plate is filled with a foam rubber sound absorber, whilst the transducers and driving blocks are wrapped in cork 32 and surrounded by potting compound 34.
  • the transducers were driven by a square wave voltage source having an 800 volt peak to peak amplitude in bursts of approximately 2 milliseconds duration. Sound pressure levels were measured in microbars peak-to-peak at a distance of 8 feet from the transducer using an appropriately calibrated Bruel and Kjaer condenser microphone type 4133.
  • the system shown in Figure 1 was constructed using a member 10 of aluminum having an upper surface 12.5 cm in diameter.
  • the system was first tested with the rings 16, 18 and disc 20 omitted, at three different resonant frequencies. At the lowest frequency tested, 7.09 KHz, the member 10 acted essentially as a piston, and a radiation pattern was observed with fairly good directional properties, the axial lobe having a 3 dB beam width of about 20°, with all side lobes more than 12 dB down, but the coupling into air was poor.
  • the maximum sound pressure level measured occurred on the axis of the transducer and was 120 microbars peak-to-peak.
  • the Q of the system was unacceptably high for pulse echo-ranging applications.
  • the member 10 was radiating essentially in the flexural mode, and the radiation pattern showed only a small central lobe with much larger side lobes, such a pattern being unsuitable for most echo-ranging techniques.
  • the sound pressure level on axis was only 87 whilst what of the first side lobe was 250. Almost all the energy was concentrated in the first and second side lobes.
  • the radiation pattern had deteriorated still further, and the sound pressure levels of the first and second side lobes were 140 and 125 respectively.
  • ring 16 which was of insulation grade polystyrene foam, 14.3 mm thick and 19 mm wide, resulted in slight alteration of the second of the two resonant frequencies discussed above to 16.07 KHz, but a striking change in the radiation pattern which became excellent with a 3 dB beam width of 10 0 and all side lobes more than 12 dB down.
  • the maximum sound pressure level was once more on the transducer axis and increased to 550.
  • the ring 16 was calculated, as discussed below, to provide a 180 degree phase reversal of sound radiated from the part of the disc outside the nodal circle, the position of which was determined visually by conventional means.
  • the amplitude of the electrical signal output from the transducer system due to receipt of an echo returned from a hard target at different distances was as follows: from 1.5 metres, 2.5 volts peak-to-peak, from 2.25 metres, 1.60.volts peak-to-peak; from 3 metres, 1.15 v.p.p.
  • the system was far lighter and used far less piezoelectric material than would a system operating at the same frequency and providing the same beam width, but constructed in accordance with the teaching of the Hands U. S. Patent No. 3,674,945.
  • One of the objectives of the inventor was to provide a transducer system for pulse echo-ranging applications which would provide a narrow beam width and substantial acoustic power output at frequencies lower than are economically practicable with known technology such as that of U. S. Patent No. 3,674,945.
  • An experiment was therefore carried out using an aluminum plate 10 which was 27.3 cm in diameter and 7.6 mm thick in the system configuration shown in Figure 3 (except as already mentioned for the housing).
  • the assembly of the piezoelectric elements and the loading blocks, without the plate, was first adjusted to resonate at approximately the desired resonant frequency, set at 11.8 kHz for an initial experiment, in which the outermost ring 20 was omitted and the periphery of the plate 10 was undamped.
  • the phase correcting rings 16 were of 20.6 mm thick polystyrene foam, whilst the impedance matching disc 18 and rings 20 were of 8.5 mm thick polyethylene foam, the parts being positioned so that their edges coincided with the nodal circles. After optimization of the rings it was found that the radiation pattern from the system showed a 3 dB beamwidth of 7.5°, a 12 dB beamwidth of 15°, an axial sound pressure level of 830 and side lobes more than 20 dB down. When operated in a pulse echo-ranging system, a transducer output of 1.9 v.p.p. was obtained from a hard target at a distance of 2.15 metres.
  • the plate 10 is considerably thinner than that shown in Figure 3, the edge grommet 26 and felt seal 28 of Figure 3 being omitted.
  • the rings 18 and 20 are also omitted, whilst the rings 16 are applied to alternate antinodal.zones of the plate.
  • the even numbered zones are'shown covered by rings 16, the opposite arrangement has also been used. However, it is preferred that the arrangement be such that the outermost full zone is covered, in the interests of ensuring as high a ratio as reasonably practicable of covered to uncovered area of the plate.
  • there are ten antinodal zones and five rings 16 but this number may be varied provided that any required degree of side lobe suppression can be obtained.
  • the thickness of the rings 16 relative to their material is chosen as discussed elsewhere so as to provide optimum matching of the radiating surface of the plate to the gaseous medium, usually air, into which it radiates.
  • a somewhat different driving connection is employed between the transducer elements 2 and the plate 10.
  • the loading block 22 is coupled to the plate through a post 23.
  • a filling 25 of foam, either chips or formed in situ, is used to prevent reflections within the housing cavity, being separated from the potting compound 34 by a cast-in-place polyurethane sealing membrane 27.
  • a transducer was constructed in accordance with Figure 4 using a plate 10, 24 cm in diameter and 1.3 mm in thickness, made of grade 6061-T6 aluminum.
  • the rings 16 were of low-density closed-cell polyethylene foam having a density of 0.025 gm/cc, and were 5.3 mm thick which is one quarter wavelength of sound in the material at 2lkHz, the operating frequency of the transducer.
  • the driver assembly of transducer elements, loading blocks and post was adjusted to resonate at this frequency.
  • the radiation pattern of the system at a test frequency of 21.0 kHz showed a 3 db beamwidth of 4.9°, a 12 db beamwidth of 8.3°, an axial sound pressure level of 3000 and side lobes at least 18 db down.
  • a transducer output of 5.5 v.p.p. was obtained. from a hard target at a distance of 2.25 metres.
  • the 3 db bandwidth of the echo-ranging system was 1.9 KHz, corresponding to a system (two-way) Q of 11.2. It was found that an even broader bandwidth could be obtained by offsetting the resonant frequency of the disc from that of the driver assembly, a 1.2 KHz offset of the disc resonant frequency providing a corresponding increase in bandwidth.
  • a further transducer was constructed for an operating frequency of 13 kHz in which the plate diameter was increased to 33 cm, and the thickness of the rings 16 increased to 7.6 mm to provide quarter wavelength matching.
  • the plate had 11 antinodal zones, the odd numbered zones counting from the centre being covered by rings 16.
  • the radiation pattern of the system showed a 3 db beamwidth of 4.9°, a 12 db beamwidth of 9.1°, side lobes at least 15 db down, and an axial sound pressure level of 5600.
  • a transducer output of 14.6 v.p.p. was obtained from a hard target at a distance of 2.25 metres.
  • the 3 db bandwidth of the echo-ranging system was 1 kHz, corresponding to a system Q of about 13.
  • a transducer of reduced sensitivity to moisture could be provided by deliberately detuning the matching rings 16 sufficiently that the application of moisture, dirt or other surface loading will not very greatly change the phase shift applied by the rings to the radiated sound or their radiating efficiency. Such an arrangement would not normally be advantageous, since it would not improve the output of the system in moist conditions.
  • Another approach which was tested was to make the rings of lossy material so that radiation therefrom was substantially reduced as compared with the uncovered antinodal zones. This again sacrifices the matching which can be provided by the rings, but also reduces the efficiency of the system since the rings will absorb a substantial portion of the energy applied to the plate. It was not found that results with such an arrangement were satisfactory.
  • this feature provides the possibility of stagger-tuning the drive system and the transducer elements so as further to broaden the bandwidth of the transducer system as a whole.
  • Plates having a diameter/ thickness ratio of between 25:1 and approximately 500:1 have been found to give good results but this range should not be regarded as limiting. Plates in which the ratio is large are are usually preferred, since the spacing between the nodal circles is reduced, thus permitting use of a higher order resonance for a given plate diameter.
  • a larger number of nodal rings will facilitate the avoidance of unwanted side lobes in the transducer response.
  • the Figure 2 and 3 embodiment has three nodal rings although more are desirable and the Figure 4 embodiment has 10.
  • the suitability of a material for use in the rings 16, 18 and 20 will depend on its properties as a low-loss acoustic propagation medium at the operating frequency of the system, and the relationship of its acoustic impedance to that of the plate and the gaseous medium.
  • the ratio of the acoustic impedance of the plate material to that of the rings should be of the same order as the ratio of that of the ring material to that of the gaseous medium, but a less than ideal relationship may be compensated for by other properties of the ring material.
  • the plate is aluminum
  • the gaseous medium is air
  • the ring material is polystyrene foam
  • the ratios defined above are about 400 and about 85 respectively
  • the ring material is solid polyurethane elastomer
  • they become about 8 and about 4000 respectively.
  • the material should not exhibit substantial hysteresis in the propagation of acoustic waves at the operating frequency since this will prevent proper operation and reduce efficiency. Materials with small closed cells appear to provide the best results amongst foamed materials.
  • material used for matching purposes should be an odd number of quarter wavelengths thick.
  • alternate antinodal zones also require to be covered with material (which need not be the same material) to an additional thickness providing approximately 180° phase shift as compared with sound passing through an equivalent thickness of air (or whatever other gaseous medium may be involved).
  • This thickness can be shown to be n/2f(1/C o -1/C 1 ) where n is an odd integer, f is the frequency of operation, C is the speed of sound in air and C 1 is the speed of sound in the material used.
  • phase correction and matching material are of low density material of lower acoustic impedance than the plate they usually add little mass or stiffness to the latter and thus have relatively little effect on its resonant frequency. This permits a relatively thin disc to be used so that its surface area is very large compared to its volume and thus to the energy stored within the disc. Since the rate of transfer of energy from the plate to the surrounding medium is proportional to the area of the radiating surface, the proportion of the energy stored within the plate that is transferred to the medium during each cycle is increased, and the Q of the system is thus decreased.
  • the ratio of the area of the plate to the effective area of the transducer element or elements is very large, a much smaller transducer element may be used to achieve a given transfer of energy.
  • the transducer element utilized in the various experiments described typically contain about 70 - 150 gm lead zirconate titanate, whereas a 10 k H z transducer of comparable performance constructed in accordance with U. S. Patent No. 3,674,945 would probably require of the order of 50 kilograms of expensive piezoelectric material and have a lower efficiency.
  • the coupling between the transducer elements and the vibrating plate may be modified in various ways. As already described with reference to Figure 4, good results have been obtained with an arrangement in which the transducer elements are mounted between identical loading blocks and the assembly is coupled to the plate by a short post, one end of which is attached to the assembly and the other to the plate. This post could also be replaced by a mechanical amplifier such as that described by Gallego-Juarez et al in the November 1978 issue of Ultrasonics at page 268.
  • higher order flexural mode resonance used in this specification and the appended claims is to be taken to include any form of flexural mode resonance of a plate which gives rise to at least two antinodal zones separated by a node and radiating (in the absence of the modification) in antiphase to one another.
EP81300378A 1980-04-21 1981-01-29 Système transducteur acoustique Expired EP0039986B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81300378T ATE2981T1 (de) 1980-04-21 1981-01-29 Akustischer wandler.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US14201480A 1980-04-21 1980-04-21
US142014 1993-10-28

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Publication Number Publication Date
EP0039986A1 true EP0039986A1 (fr) 1981-11-18
EP0039986B1 EP0039986B1 (fr) 1983-04-06

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EP (1) EP0039986B1 (fr)
JP (1) JPS56165497A (fr)
AT (1) ATE2981T1 (fr)
AU (1) AU532596B2 (fr)
CA (1) CA1136257A (fr)
DE (1) DE3160140D1 (fr)
MX (1) MX149462A (fr)
ZA (1) ZA81876B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3602351C1 (de) * 1986-01-27 1986-12-11 Endress + Hauser GmbH + Co., 79689 Maulburg Schallwandlersystem
DE19601656A1 (de) * 1996-01-18 1997-07-24 Teves Gmbh Alfred Bedämpfter Ultraschallwandler
DE19620133A1 (de) * 1996-05-18 1997-11-27 Endress Hauser Gmbh Co Schall- oder Ultraschallsensor
WO2014202331A1 (fr) * 2013-06-20 2014-12-24 Robert Bosch Gmbh Dispositif de détection d'environnement comprenant un transducteur ultrasonore et véhicule automobile équipé d'un dispositif de détection d'environnement de ce type
WO2014202333A1 (fr) * 2013-06-20 2014-12-24 Robert Bosch Gmbh Dispositif de détection d'environnement comprenant un transducteur ultrasonore et véhicule automobile équipé d'un dispositif de détection d'environnement de ce type

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Publication number Priority date Publication date Assignee Title
DE19758243A1 (de) * 1997-12-30 1999-07-15 Endress Hauser Gmbh Co Schallwandlersystem
US8186229B2 (en) * 2010-01-06 2012-05-29 Daniel Measurement And Control, Inc. Ultrasonic flow meter having a port cover assembly
US9050628B2 (en) 2012-01-30 2015-06-09 Piezotech Llc Pulse-echo acoustic transducer

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FR1546591A (fr) * 1966-08-10 1968-11-22 Univ Ohio State Transducteurs électro-mécaniques
US4078160A (en) * 1977-07-05 1978-03-07 Motorola, Inc. Piezoelectric bimorph or monomorph bender structure

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US3218488A (en) * 1961-08-01 1965-11-16 Branson Instr Transducer
JPS437677Y1 (fr) * 1965-01-02 1968-04-05
JPS5929816B2 (ja) * 1975-08-20 1984-07-23 松下電器産業株式会社 超音波探触子

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Publication number Priority date Publication date Assignee Title
FR1546591A (fr) * 1966-08-10 1968-11-22 Univ Ohio State Transducteurs électro-mécaniques
US4078160A (en) * 1977-07-05 1978-03-07 Motorola, Inc. Piezoelectric bimorph or monomorph bender structure

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Title
Research Disclosures-Product, Licensing Index, June 1971, No. 86, Havant, GB "Ultrasonic Apparatus", pages 38-39 * whole article * *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3602351C1 (de) * 1986-01-27 1986-12-11 Endress + Hauser GmbH + Co., 79689 Maulburg Schallwandlersystem
FR2593660A1 (fr) * 1986-01-27 1987-07-31 Endress Hauser Gmbh Co Systeme de convertisseur acoustique.
US4768615A (en) * 1986-01-27 1988-09-06 Endress U. Hauser Gmbh U. Co. Acoustic transducer system
DE19601656A1 (de) * 1996-01-18 1997-07-24 Teves Gmbh Alfred Bedämpfter Ultraschallwandler
DE19601656B4 (de) * 1996-01-18 2009-07-16 Valeo Schalter Und Sensoren Gmbh Bedämpfter Ultraschallwandler
DE19620133A1 (de) * 1996-05-18 1997-11-27 Endress Hauser Gmbh Co Schall- oder Ultraschallsensor
US5726952A (en) * 1996-05-18 1998-03-10 Endress + Hauser Gmbh + Co. Sound or ultrasound sensor
DE19620133C2 (de) * 1996-05-18 2001-09-13 Endress Hauser Gmbh Co Schall- oder Ultraschallsensor
WO2014202331A1 (fr) * 2013-06-20 2014-12-24 Robert Bosch Gmbh Dispositif de détection d'environnement comprenant un transducteur ultrasonore et véhicule automobile équipé d'un dispositif de détection d'environnement de ce type
WO2014202333A1 (fr) * 2013-06-20 2014-12-24 Robert Bosch Gmbh Dispositif de détection d'environnement comprenant un transducteur ultrasonore et véhicule automobile équipé d'un dispositif de détection d'environnement de ce type

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MX149462A (es) 1983-11-08
CA1136257A (fr) 1982-11-23
JPS56165497A (en) 1981-12-19
JPH0134000B2 (fr) 1989-07-17
ATE2981T1 (de) 1983-04-15
DE3160140D1 (en) 1983-05-11
AU6823881A (en) 1981-10-29
EP0039986B1 (fr) 1983-04-06
AU532596B2 (en) 1983-10-06
ZA81876B (en) 1982-02-24

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