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EP0472085B1 - Capteur d'ultrason - Google Patents

Capteur d'ultrason Download PDF

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Publication number
EP0472085B1
EP0472085B1 EP91113510A EP91113510A EP0472085B1 EP 0472085 B1 EP0472085 B1 EP 0472085B1 EP 91113510 A EP91113510 A EP 91113510A EP 91113510 A EP91113510 A EP 91113510A EP 0472085 B1 EP0472085 B1 EP 0472085B1
Authority
EP
European Patent Office
Prior art keywords
ultrasonic sensor
signal electrode
electrode
layer
coupling
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
EP91113510A
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German (de)
English (en)
Other versions
EP0472085A1 (fr
Inventor
Ulrich Dipl.-Ing. Schätzle
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.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
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
Application filed by Siemens AG, Siemens Corp filed Critical Siemens AG
Publication of EP0472085A1 publication Critical patent/EP0472085A1/fr
Application granted granted Critical
Publication of EP0472085B1 publication Critical patent/EP0472085B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • B06B1/0688—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 with foil-type piezoelectric elements, e.g. PVDF
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S310/00—Electrical generator or motor structure
    • Y10S310/80—Piezoelectric polymers, e.g. PVDF

Definitions

  • the invention relates to an ultrasonic sensor, in particular for shock wave measurements, comprising a piezoelectric film, a signal electrode and a ground electrode.
  • ultrasonic sensors are fundamentally suitable both for local pressure measurement and for field measurement in ultrasonic fields.
  • the sensors have to meet a number of requirements, namely that the sensors have a sufficiently high upper cut-off frequency, a sufficiently long service life, in particular when measuring focused shock waves, and a sufficiently high sensitivity for field measurement.
  • a further disadvantage is that the measurement results are falsified by non-linear compression properties of the liquid located between the piezoelectric film and the electrodes, cavitation effects in this liquid and positional influences may occur.
  • the presence of liquid between the piezoelectric film and the electrodes can be avoided if, as in the case of EP-A-0 351 285, electrodes are deposited on both sides of the piezoelectric film which completely cover the surface of the piezoelectric film with which they are associated cover.
  • both types of sensors do not have a satisfactory service life when subjected to high-intensity shock waves.
  • the invention has for its object to provide an ultrasonic sensor of the type mentioned in such a way that the specified requirements are met, the disadvantages associated with the presence of a liquid between the electrodes and the piezoelectric film are avoided and the conditions are created for ultrasonic sensors with the respective application to be able to implement adapted sensitivity.
  • an ultrasound sensor in particular provided for shock wave measurements, which has a piezoelectric film polarized at least in one area, a signal electrode arranged on one side of the piezoelectric film and a ground electrode arranged on the other side of the piezoelectric film, wherein A dielectric coupling layer is provided at least between the signal electrode and the piezoelectric film or between the ground electrode and the piezoelectric film, the piezoelectric film, the signal electrode, the ground electrode and the coupling layer being components of a multilayer structure and the signal electrode and the polarized region the piezoelectric film in a the pressure sensitive sensor surface overlap the forming area.
  • the coupling layer is separated from the piezoelectric film as well as from the signal electrode or the ground electrode by a thin layer of a material serving for acoustic coupling belonging to the multilayer structure.
  • the piezoelectric film, the signal electrode and the ground electrode are components of a multilayer structure
  • the ultrasonic sensor according to the invention has a robust structure and is therefore predestined for shock wave measurements.
  • the problems associated with the presence of liquids between the electrodes and the piezoelectric film are avoided as a result of the multilayer structure, since the capacitive tapping of the surface charges takes place through the coupling layer (s).
  • the sensitivity of the ultrasonic sensor according to the invention can easily be adapted to the respective requirements by selecting the distances between the signal or ground electrode on the one hand and the piezoelectric film on the other hand by appropriate selection of the thickness of the coupling layer (s) according to the respective requirements are, whereby a smaller distance leads to a higher sensitivity.
  • a decreasing thickness of the coupling layer (s) goes hand in hand with a reduction in the service life of the ultrasonic sensor according to the invention, since the coupling layer (s), which must be or must be elastically flexible, perform an important protective function by fulfilling the elastic impact energy of the Dampens or dampens shock waves due to their elastic compliance.
  • the thickness of the coupling layer (s) should therefore correspond to at least twice, preferably at least five times the thickness of the piezoelectric film.
  • the material of the coupling layers (s) is preferably a material whose acoustic impedance is matched to that of the medium in which the ultrasonic sensor is to be used, since signal falsifications due to reflections at the interfaces of the coupling layer (s) are then largely excluded are.
  • Another essential advantage of the ultrasonic sensor according to the invention consists in the fact that the size of the sensor surface and thus the spatial resolution achievable in measurements with the ultrasonic sensor according to the invention can be easily adapted to the respective needs by the dimensions and the shape of the area in which the signal electrode and the piezoelectric foil overlap the respective needs be chosen accordingly.
  • High upper limit frequencies of the ultrasonic sensor according to the invention can easily be achieved due to the use of a piezoelectric film, which can be very thin (10 ⁇ m).
  • the layer separating the coupling layer both from the piezoelectric film and from the signal or ground electrode serves for the acoustic coupling of the layers of the multilayer structure adjacent to it.
  • the layer should have a thickness which is significantly less, for example 5 times, preferably 10 times less than the thickness of the piezoelectric film which is decisive for the upper limit frequency of the ultrasonic sensor, in order to exclude harmful acoustic effects.
  • Silicone rubber is particularly suitable as the material for the layer. On the one hand, due to its properties, this material is able to effect the required acoustic coupling of the layers to one another. On the other hand, due to its adhesive properties, silicone rubber can contribute to the mechanical cohesion of the adjacent layers of the multilayer structure or can achieve this completely.
  • At least the signal electrode or the ground electrode is expediently provided with an elastically flexible, preferably electrically insulating cover layer as a component of the multilayer structure.
  • This measure further improves protection of the ultrasonic sensor against the action of shock waves, since the electrode (s) are also protected.
  • the protective effect increases with the thickness of the cover layer, the upper limit frequency of the ultrasonic sensor decreasing with increasing thickness of the cover layer due to increasing attenuation of the high-frequency acoustic signal components.
  • the cover layer is also preferably for the reasons explained in connection with the coupling layer (s) a material is formed whose acoustic impedance is matched to that of the medium in which the ultrasonic sensor is used.
  • a particularly advantageous embodiment of the invention provides that the signal electrode and the piezoelectric film are each arranged in a strip shape and crossing one another, the simple shape of the film and the signal electrode allowing simple production and unproblematic assembly of the ultrasonic sensor.
  • the ultrasound sensor has a support body which carries the multilayer structure and is provided with a curved end face, the sensor surface being located in the region of the curved end face. It is then very easily possible to produce the multilayer structure in which the individual components are glued to one another on the support body, the homogeneous and essential for the proper functioning of the ultrasonic sensor being in the area of the sensor surface gas bubble-free bonds can be produced very easily due to the curved end face of the support body.
  • the components of the multilayer structure are wound overlapping one another on the preferably at least substantially cylindrical support body. This then results in a spiral arrangement of the components of the multilayer structure, which, due to the fact that the components of the multilayer structure can be wound and glued to one another by exerting a tensile force, the manufacture of the required in a safe and again simpler manner enables homogeneous and gas bubble-free bonds.
  • the ultrasonic sensor according to FIGS. 1 to 4 has a film strip 1 of a piezoelectric polymeric material as the most important element, the film strip 1 being polarized in its entirety.
  • Ultrasonic or shock waves impinging on the film strip 1 corresponds to the direction of arrow III in FIG. 1, and generate the surface charge vibrations corresponding to the ultrasonic or shock waves in their temporal course.
  • These are tapped with the aid of a likewise strip-shaped signal electrode 2 and a large-area mass electrode 3 and fed via lines 4.5 connected to the electrodes 2, 3 to a suitable amplifier (not shown), at the output of which an amplified signal which reflects the time course of the surface charge oscillations is available stands.
  • the surface charge vibrations are tapped capacitively, since a coupling layer 6 or 7 of a dielectric material is provided between the signal electrode 2 and the film strip 1 as well as between the film strip 1 and the ground electrode 3.
  • the ground electrode 3 is provided with an elastic, electrically insulating cover layer 8.
  • the strip-shaped signal electrode 2 crosses the film strip 1 at an angle of 90 °, so that the film strip 1 and the signal electrode 2 overlap in a small area, the area of which is the product of the width of the Film strip 1 and the signal electrode 2 results.
  • the area mentioned is the sensor surface 9 that is pressure-sensitive for both negative and positive pressure.
  • the cover layer 8, the ground electrode 3, the coupling layer 7, the film strip 1, the coupling layer 6 and the signal electrode 2 form a multilayer structure which is attached to a supporting body 10 with a square cross section, which extends around a parallel to the central axis of the film strip 1 Axis has convexly curved end face 11, in the area of which the sensor surface 9 is located.
  • the multilayer structure - the thicknesses of the individual layers are exaggerated in FIGS. 1 to 4 for reasons of clarity - is preferably produced in such a way that the individual elements, starting with the signal electrode 2 glued onto the carrier body 10 by means of a suitable adhesive of the ultrasonic sensor in the sequence and arrangement shown in FIGS. 1 and 2 are connected to one another by means of suitable adhesives.
  • the curved end face 11 of the supporting body 10 facilitates the mounting of the individual layers and the production of homogeneous and gas-bubble-free bonds in the area of the sensor area 9.
  • the adhesive layers designated S1 to S4 are shown in FIG. 4.
  • the piezoelectric film 1 is embedded in the adhesive layer S1 such that the piezoelectric film 1 is separated both from the coupling layer 6 and from the coupling layer 7 by an adhesive layer S1a to S1b.
  • the adhesive layer S2, in which the signal electrode 2 is embedded similarly to the piezoelectric film in the adhesive layer S1 is located between the coupling layer 6 and the support body 10.
  • the signal electrode 2 is accordingly separated from the coupling layer 6 by the adhesive layer S2a and from the support body 10 by the adhesive layer S2b.
  • the adhesive layer S3 is located between the ground electrode 3 and the coupling layer 7.
  • the adhesive layer S4 is provided between the ground electrode 3 and the cover layer 8. It is understood that the thicknesses of the adhesive layers are exaggerated in relation to the thicknesses of the other components in FIG. 4.
  • the large-area ground electrode 3 which, like the cover layer 8 and the coupling layers 6 and 7, extends over the entire width B of the supporting body 10, serves in addition to its function as an electrode for the electrical shielding of the ultrasonic sensor.
  • the film strip 1 is preferably made of polyvinylidene fluoride (PVDF). But there are also other piezoelectric ones activatable polymer films in question.
  • PVDF polyvinylidene fluoride
  • the thickness of the film strip 1 decisively determines the upper cut-off frequency of the sensor and should not substantially exceed 100 ⁇ m for the measurement of shock waves with very steep pulse edges, the rise times of which can be less than a microsecond.
  • the width of the film strip is between 1 and 2 mm.
  • the materials of the coupling layers 6 and 7, the cover layer 8 and the supporting body 10 should be insensitive to shock waves, that is to say elastically compliant and to the acoustic impedance of the medium in which the measurements are carried out by means of the ultrasound sensor and the ultrasound or shock waves propagate accordingly, have matched acoustic impedances.
  • Suitable materials for measurements in water are, for example, soft rubber or soft PVC.
  • the acoustic impedance of these materials can be adjusted in each case by means of the plasticizer content, the acoustic impedance decreasing with increasing plasticizer content.
  • the materials mentioned also have good dielectric properties.
  • the thicknesses of the coupling layers 6 and 7 should not substantially exceed 1000 ⁇ m, because otherwise the sensitivity of the ultrasonic sensor will be too low due to the then relatively large distance between the signal electrode 2 and the ground electrode 3 and the film strip 1. Prototypes were realized, the sensitivity of which depending on the thickness of the coupling layers is 6.7 15 mV / MPa or 340 mV / MPa.
  • the thickness of the cover layer 8 should not significantly exceed 2000 ⁇ m, since otherwise an increase in the attenuation of high-frequency signal components results in a limitation of the measurable steepness of rise in shock waves or the upper limit frequency in ultrasonic waves.
  • the coupling layers 6 and 7 should each be at least twice, preferably at least five times, and the cover layer 8, for example, at least four times, preferably at least ten times as thick as the piezoelectric film 1 used.
  • Thin stainless steel foil which also has sufficient electrical conductivity, is suitable as material for the signal electrode 2 and the ground electrode 3 because of its good resistance to corrosion and shock waves.
  • foils of other electrically conductive materials can be used, the durability of which is comparable to that of stainless steel foils.
  • their thickness, the thickness of the piezoelectric foil 1 and thus a maximum of 100 ⁇ m should not significantly exceed, since then the thickness of the signal electrode 2 and the ground electrode 3 is so small compared to the wavelength corresponding to the upper limit frequency of the ultrasonic sensor that no impairments due to reflections are to be expected.
  • the width of the signal electrode is between 1 and 2 mm.
  • a suitable adhesive for connecting the individual layers is, for example, silicone rubber, which has an acoustic impedance that is approximately matched to water.
  • the thickness of the adhesive layers S1, S1a, S2, S2a, S2b, S3 and S4 present between the individual layers, which are only shown in FIG. 4, should be significantly less (for example at least by a factor of 5, preferably 10) than the thickness of the layer to be glued.
  • the adhesive layers S1, S1a, S1b, S2, S2a, S2b, S3 and S4 ensure the cohesion of the multilayer structure. They also serve to acoustically couple adjacent layers of the multilayer structure and must therefore be free of gas bubbles. This applies in particular to the adhesive layers S1a and S1b which bring about the acoustic coupling of the piezoelectric film 1 to the coupling layers 6 and 7, respectively.
  • the sensor described is extremely robust due to its multilayer structure attached to the support body 10, it has the further significant advantage that its physical properties largely depend on geometric sizes that can be influenced by simple design measures.
  • the widths of the film strip 1 and the signal electrode 2 influence the spatial resolution, the directional characteristic and the sensitivity of the ultrasonic sensor.
  • the spatial resolution increases with decreasing width of the elements mentioned, while the sensitivity decreases.
  • the directional characteristic of the ultrasonic sensor depends on the ratio in which the widths of the film strip 1 and the signal electrode 2 are in relation to one another and on the crossing angle of the elements mentioned.
  • the service life, the sensitivity and to a certain extent the upper cut-off frequency of the ultrasonic sensor depend on the thicknesses of the coupling layers 6 and 7.
  • the service life of the ultrasonic sensor increases with increasing thickness of the coupling layers 6 and 7, while at the same time its sensitivity decreases.
  • the upper limit frequency decreases with increasing thickness of the coupling layers 6 and 7, since in these high-frequency signal components experience a higher acoustic damping than comparatively low-frequency signal components.
  • the support body 10 can also have a circular cross section.
  • the end face 11 of the supporting body which carries the multilayer structure then has the shape of a hemisphere.
  • the exemplary embodiment shown in FIGS. 5 to 8 differs from the previously described first in that a cylindrical support body 12 is provided, on which the components of the multilayer structure are spirally overlapping. Accordingly, the signal electrode 13 is first wound on the support body 12, the signal electrode 13 looping around the support body 12 at an angle of slightly more than 180 °. The procedure is such that the one in FIG. 5 left end of the signal electrode 13, which is of strip-like design analogous to the signal electrode 2, is glued to the support body 12. After this bond has set, the signal electrode 13 is wound around the support body 12 coated with a suitable adhesive while exerting a tensile force.
  • a coupling strip 14 is bonded at one end to the support body 12 and the signal electrode 13 in such a way that it connects the right end of the signal electrode 13 in FIG. 5 by an angle of, for example, 15 to 30 ° overlaps.
  • the coupling strip 14, which, unlike the signal electrode 13, extends over the entire width of the support body 12, is wound around the support body 12 provided with the signal electrode 13 with the addition of a suitable adhesive in just under two turns while exerting tension. 5
  • a metal strip 15 serving as a connection for the signal electrode 13 is wound between the first turn of the coupling strip 14 and the signal electrode 13 in the region of the left end of the signal electrode 13 in FIG. 5.
  • the metal strip 15 protrudes laterally over the support body 12. So that a perfect electrically conductive connection of the metal strip 15 with the signal electrode 13 is present, care must be taken to ensure that there is no adhesive between the two.
  • the piezoelectrically activated film strip 16 is placed between the first and the second turn of the coupling strip 14 and is arranged such that it crosses the strip-shaped signal electrode 13 at an angle of 90 °, the central axis of the film strip 16 being parallel to the central axis of the cylindrical support body 12 runs.
  • the area in which the signal electrode 13 and the film strip 16 overlap is again the sensor surface 17 of the ultrasonic sensor, which is sensitive to both negative and positive pressure and is located in the area of the lateral surface of the cylindrical support body 12.
  • the two turns of the coupling strip 14 form coupling layers 18 and 19, which correspond to the coupling layers 6 and 7 in the case of the embodiment described above.
  • the ground electrode 20 extending over the entire width of the support body 12 is wound in an almost complete turn. The procedure is such that one end of the ground electrode 20 is first glued to the end of the second turn of the coupling strip 14. After this bond has set, the ground electrode 20, which incidentally extends over the entire width of the supporting body 12, is wound around the outer turn of the coupling strip 14 with the addition of adhesive while exerting tension.
  • a second metal strip 21 is wound as an electrical connection for the ground electrode 20 between the latter and the outer turn of the coupling strip 14.
  • the metal strip 21 protrudes laterally beyond the support body 12. To ensure perfect electrical contact, there must be no adhesive between the metal strip 21 and the ground electrode 20.
  • FIG. 8 which shows the detail B according to FIG. 5, the mentioned adhesives complement one another to form a single spiral-shaped adhesive layer S in which the signal electrode 13 and the piezoelectrically activated film strip 16 are embedded, similarly to the exemplary embodiment described above.
  • the film strip 16 is thus separated from the coupling layer 18 by the adhesive layer Sa and from the coupling layer 19 by the adhesive layer Sb.
  • the adhesive layer Sc and Sd separate the signal electrode 13 from the coupling layer 19 and the support body 12, respectively.
  • the layers 13, 14 and 20 can advantageously be glued to one another at their overlap locations, even if the required length of the layers is known precisely, before winding onto the support body 12.
  • the "layer chain” thus created can then be wound in one operation with the addition of adhesive and with the application of tension to the support body 12 without having to wait for setting times.
  • the multilayer structure described has an essentially cuboid-shaped holding part 22 through an adhesive layer located between the ground electrode 20 and the holding part 22 S5 connected, wherein the holding part 22, the width of which corresponds to that of the supporting body 12, has a concave recess 23 on its one end face for receiving the multilayer structure mentioned.
  • the multilayer structure is bonded to the holding part 22 between the ground electrode 20 and the surface of the recess 23.
  • the multilayer structure also comprises the cover layer 24, which extends over the entire width of the support body 12 and whose area surrounding the ground electrode 20 is glued to it.
  • the free ends of the cover layer 24 are glued to the mutually opposite side surfaces of the holding part 22.
  • the individual layers of the ultrasonic sensor according to FIGS. 4 to 8 match those of the ultrasonic sensor according to FIGS. 1 to 3.
  • the function of the adhesive layers S, Sa, Sb, Sc, Sd, S5 also corresponds to the function of the corresponding adhesive layers of the previously described embodiment.
  • silicone rubber is suitable as an adhesive for connecting the individual layers.
  • the adhesive layers present between the individual layers are not shown in FIGS. 5 to 7.
  • the adhesive which is in the column shown in FIGS. 5 and 6 in the region of the signal electrode 13, the film strip 16, the metal strips 15 and 21 and the ends of the coupling strip 14, which are extremely narrow in practice, is also present for reasons of clarity, not shown in the figures mentioned, but shown in FIG.
  • the multilayer structure has in practice out-of-roundness which is negligibly small compared to that shown in FIG. 5.
  • the thicknesses of the adhesive layers are again exaggerated in FIG. 8 compared to the thicknesses of the other layers.
  • the cover layer 24 in such a way that it completely wraps around the ground electrode 20.
  • the multilayer structure would be attached to the holding part 22 by gluing between the cover layer 24 and the surface of the recess 23 adapted to the radius of curvature of the cover layer 24.
  • cylindrical support body 12 instead of the cylindrical support body 12, differently shaped support bodies can also be provided. It is essential, however, that these have a convexly curved surface in the area of the sensor surface 17, so that no air bubbles can form when the components of the multilayer structure are wound onto the support body in the area of the sensor surface 17.
  • the avoidance of air bubbles and the formation of a homogeneous bond are particularly favored by the tensile force which is continuously possible in the case of the ultrasonic sensor according to FIGS. 4 to 8 when the individual layers are wound.
  • the ultrasonic sensor can also be designed as a self-supporting multilayer structure, with the result that a component comparable to the supporting body 10 is then unnecessary.
  • the film strip 1 does not have to be polarized in its entirety. Rather, it is sufficient if a sufficiently large piezoelectrically activated film area is present in the area in which the film strip 1 and signal electrode 2 cross.
  • adhesive layers need not necessarily be between the layers. It can rather, in particular between the coupling layers and the piezoelectric film and the signal or ground electrode, layers of a viscous, non-adhesive substance with suitable acoustic properties may be provided.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Claims (9)

  1. Capteur d'ultrasons, notamment pour des mesures d'ondes de choc, comportant une feuille piézoélectrique (1; 16), dont au moins une zone est polarisée, une électrode de transmission de signal (2;13) disposée sur l'une des faces de la feuille piézoélectrique (1;16) et une électrode de masse (3;20) disposée sur l'autre face de la feuille piézoélectrique (1;16), une couche diélectrique de couplage flexible élastiquement (6 ou 7; 18 ou 19) étant disposée au moins entre l'électrode de transmission de signal (2;13) et la feuille piézoélectrique (1;16) ou entre l'électrode de masse (3;20) et la feuille piézoélectrique (1;16), la feuille piézoélectrique (1;16), l'électrode de transmission de signal (2;13), l'électrode de masse (3;20) et la couche de couplage (6 ou 7; 18 ou 19) faisant partie d'une structure à couches multiples, tandis que l'électrode de transmission de signal (2;13) et la zone polarisée de la feuille piézoélectrique (1;16) se recouvrent dans une partie formant une surface (9;17) de capteur, sensible à la pression.
  2. Capteur d'ultrasons suivant la revendication 1, caractérisé par le fait qu'au moins l'électrode de transmission de signal (2;13) ou l'électrode de masse (3;20) comporte une couche de revêtement flexible élastiquement (8;24) faisant partie de la structure à couches multiples.
  3. Capteur d'ultrasons suivant la revendication 1 ou 2, caractérisé par le fait que l'électrode de transmission de signal (2;13) et la feuille piézoélectrique (1;7) possèdent chacune une configuration en forme de bande et sont disposées de manière à se croiser.
  4. Capteur d'ultrasons suivant l'une des revendications 1 à 3, caractérisé par le fait qu'au moins l'électrode de masse (3;20) ou l'électrode de transmission de signal (2;13) est formée par une feuille conductrice de l'électricité et en un matériau résistant aux ondes de choc.
  5. Capteur d'ultrasons suivant la revendication 4, caractérisé par le fait que la feuille est en acier spécial.
  6. Capteur d'ultrasons suivant l'une des revendications 1 à 5, caractérisé par le fait que la feuille piézoélectrique (1;16) est en fluorure de polyvinylidène (PVDF).
  7. Capteur d'ultrasons suivant l'une des revendications 1 à 6, caractérisé par le fait qu'au moins une couche de couplage (6 ou 7; 18 ou 19) est réalisée en caoutchouc mou ou en PVC mou.
  8. Capteur d'ultrasons suivant l'une des revendications 1 à 7, caractérisé par le fait que le capteur d'ultrasons comporte un corps de support (10;12), qui porte la structure à couches multiples et qui comporte une surface courbée (11;25), dont la courbure est convexe, la surface (9;17) du capteur étant située dans la zone de la surface courbée (11;25).
  9. Capteur d'ultrasons suivant la revendication 8, caractérisé par le fait que les constituants de la structure à couches multiples sont enroulés en superposition sur le corps de support (12), qui est de préférence au moins sensiblement cylindrique.
EP91113510A 1990-08-24 1991-08-12 Capteur d'ultrason Expired - Lifetime EP0472085B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP90116268 1990-08-24
EP90116268 1990-08-24

Publications (2)

Publication Number Publication Date
EP0472085A1 EP0472085A1 (fr) 1992-02-26
EP0472085B1 true EP0472085B1 (fr) 1995-01-11

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US (1) US5159228A (fr)
EP (1) EP0472085B1 (fr)
JP (1) JP2947991B2 (fr)
DE (1) DE59104214D1 (fr)

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US4555953A (en) * 1984-04-16 1985-12-03 Paolo Dario Composite, multifunctional tactile sensor
US4609845A (en) * 1984-07-06 1986-09-02 Raychem Corporation Stretched piezoelectric polymer coaxial cable
US4824107A (en) * 1985-10-10 1989-04-25 French Barry J Sports scoring device including a piezoelectric transducer
US4734611A (en) * 1985-12-20 1988-03-29 Siemens Aktiengesellschaft Ultrasonic sensor
US4911172A (en) * 1988-03-28 1990-03-27 Telectronics Pacing Systems, Inc. Probe tip ultrasonic transducers and method of manufacture
FR2634088B1 (fr) * 1988-07-11 1991-05-31 Inst Francais Du Petrole Capteur piezo-electrique comportant au moins une paire d'elements sensibles souples de grande longueur

Also Published As

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US5159228A (en) 1992-10-27
JPH04245899A (ja) 1992-09-02
DE59104214D1 (de) 1995-02-23
EP0472085A1 (fr) 1992-02-26
JP2947991B2 (ja) 1999-09-13

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