Abstract: The invention provides an electrode for piezoelectric composites having high acoustic attenuation. The electrode is composed of a first layer having high elasticity and lower conductivity and of a second layer lying thereabove that has higher conductivity. The invention also provides a method for the manufacture thereof. The first layer is an intrinsically conductive plastic directly deposited on the ceramic whose polymerization is initiated by chemical or anodic oxidation of the corresponding monomers. The second layer is fashioned of adequately conductive metal and is preferably first sputtered on or vapor-deposited in a thinner layer and is then subsequently electrolytically reinforced. Piezoelectric composites that exhibit high acoustic attenation and, thus, prevent an acoustic crosstalk between the individual transducer elements can be manufactured from piezoelectric ceramic lamina or foils provided with such electrodes.

Abstract: Piezopolymer actuator, wound in a bifilar fashion on two pins, is operated in a compressive mode without buckling. In addition to constraining motion of the winding along the surface of the pins, the pins also provide wide area electrical contacts with conductive electrodes on the surfaces of the piezopolymer strip. The electrodes consist of a thin film of metallization coated with graphite. Graphite coating heals microcracks in metallization, adds body to the piezopolymer strip, and lubricates winding-pin interfaces. Modular linear arrays of actuators are readily built from a single strip of piezopolymer. Linear array modules are in turn clamped together to form a two-dimensional array. Typical application is a tactile array for the blind.

Abstract: Disclosed are new piezoelectric/pyroelectric materials of polarized homopolymer and copolymers of trifluorovinyl acetate. Also disclosed is a unique predictive relationship for determining the piezoelectricity of unknown material.

Abstract: A towed piezoelectric cable having a plurality of receiver element units which are arranged on a nonshrinking flexible core with leaving a buffer zone therebetween, each of said receiver element units having two piezoelectric elements which are polarized in a predetermined direction, and are provided with inner electrodes connected to each other and outer electrodes between which an output signal is produced, respectively, the assembly of said receiver element units and said flexible core being contained in a flexible tube which is filled with an insulating oil.

Abstract: Laminates of polyvinylidene fluroride (PVDF) are employed as piezoelectric sensors and actuators which can sense and/or generate complex motions that include bending, stretching, and twisting components. The laminates can be attached directly to a mechanical structure whose motions are to be sensed and/or controlled. By skewing the principal axes of each of the lamina in the laminate with respect to one another, the laminate is responsive not only to bending motions, but to torsional motions as well. Surface electrodes are disposed on the top and bottom sides of each of the lamina to either sense voltage generated by the lamina in response to motion imparted thereto, or supply voltage to the lamina to induce motion therein. The shape of the surface electrode patterns can be varied to control the particular components of motion to which each of the lamina is responsive (e.g., bending modes). The polarization profile in each of the lamina can also be varied for this purpose.

Abstract: This invention relates to a process for making polarized material by forming a solution of a material capable of being polarized with a polarization solvent which can be removed by evaporation. The material in solution is poled to provide a polarized material which is free or substantially free of mechanically-induced orientation and which polarization is essentially stable up to the crystal melting point of the polar crystals or to softening point of the polarized material if non-crystalline. The polarization solvent can be removed from the solution as desired either to a reduced level or completely, such as during poling or before or after poling.

Abstract: Piezoelectric transducer for the production of, for example, hydrophones, with the transducer including a plurality of sensitive coaxial elements interconnected so as to compensate for the effects of accelerations and deflections.A transducer includes at least one pair of sensitive elements composed of sections of radially polarized coaxial piezoelectric cables having an opposing orientation, with an external armouring of one being connected with an internal armouring of the other, and vice versa. By increasing the number of parts of sensitive elements and selecting the relative disposition, it is possible to improve the immunity of the transducer to noise due to accelerations and deflections, regardless of the direction or the need to license a direction where the transducer is sensitive to such noise. A predetermined number of pairs of sensitive elements can be combined around a central column for accommodating connectors or cables.To be applied, for example, to the production of hydrophones.

Abstract: Piezoelectric polymer film, when conformably adhered to inner or outer surfaces of an inflated balloon, functions as a microphone when the pressure of sound waves causes the film to vibrate and generate an electrical signal. The film may be in the form of an helical strip, individual strips electrically serially connected, or may itself form the inflatable material. A receiving device is electrically coupled with the electrodes formed on the piezoelectric film for processing the electrical signals generated by the vibrating piezoelectric polymer film.

Abstract: Underwater piezoelectric arrangement in which it comprises two piezoelectric elements made of piezoelectric ceramic-polymer composites and juxtaposed to form a single layer structure, one of the element(s) having larger hydrophone constant than that of the other element(s), and by noise cancelling of the piezoelectric assembly there can be selectively detected only charges or voltages generated by acoustic waves which acts on each element.

Abstract: A geophone designed to measure the vibrations of bodies, especially vibrations in the earth's crust, comprises two-strip sensors made of piezoelectric polymer, embedded by one end in the geophone casing and resting freely, by one side, on the inertial mass of the geophone, thus enabling the making of geophones with a very wide pass-band.

Abstract: To compensate for the effect of external parameters on piezoelectric sensors connected to a charge amplifier, a small portion of this sensor is used to form the feedback capacitor of the amplifier. These parameters then have the same effect on the sensor and on the capacitor, thus making it possible to provide compensation to hydrophones made of piezoelectric polymer material.

Abstract: A drop detector having a piezoelectric membrane mounted to a substrate is presented. When a drop strikes the piezoelectric membrane, the membrane vibrates at a selected resonant frequency. The resonant frequency is selected to enhance the sensitivity of the drop detector and the signal-to-noise ratio of the output. The value of the selected resonant frequency depends on the type of material used for the piezoelectric membrane, the thickness of the membrane, the mounting of the membrane to the substrate, and other parameters such as the coating on the membrane. The vibrations of the membrane produce an output signal having a frequency equal to the selected resonant frequency. Since the frequency of the output signal is known, the output signal can be filtered with a bandpass filter to enhance the signal-to-noise ratio of the output signal. The resulting membrane drop detector is a high sensitivity, high signal-to-noise ratio drop detector.

Abstract: An acoustic transducer array includes a number of transparent continuous aperture transducer elements which are aimed at various angular sectors in a field of view and are embedded in an acoustically transparent material such as casting resin. Each transducer provides a beamformed output, and the transparency of the elements ensures that each element observes an acoustic field that is unperturbed by the other elements. A high resolution and a wide field of view are obtained by overlapping the transducer elements so that each element captures an increased area of acoustic signal. Preferably, the transducer elements are cut from thin, flexible metalized sheets of voided piezeoelectric polymer such as polyvinylidene fluoride or polyvinyl fluoride co-polymer. The polymer transducers are broad band in nature, and permit multiple frequency, multiple beam sonar configurations.

Abstract: A multi-color printer using a sonic toner release development system to provide either partial or full color copies with minimal degradation of developed toner patterns by subsequent over-development with additional colors and minimal back contamination of developer materials. Multiple scanning beams, each modulated in accordance with distinct color image signals, are scanned across the printer's photoreceptor at relatively widely separated points, there being buffer means provided to control timing of the different color image signals to assure registration of the color images with one another. Each color image is developed prior to scanning of the photoreceptor by the next succeeding beam. After developing of the last color image, the composite color image is transferred to a copy sheet. Development is accomplished by vibrating the surface of a toner carrying member and thereby reducing the net force of adhesion of toner to the surface of the toner carrying member.

Abstract: A device for assessing stresses in mechanical processing of agricultural or manufactured products has a core 11 and, adjacent to the surface a layer of piezo-electric plastic material 13. The device has physical characteristics simulating those of the product. In use the device is included in a batch of products being processed and the piezo-electric signals caused by the stresses are analyzed by electronic equipment either external to or contained within the device to locate when and where damaging stresses occurred.

Abstract: Disclosed is a device for generating an analog output signal indicative of an impact to a transucer. The tranducer may be mounted on protective equipment utilized in various martial arts fields, such as headgear, hand or footgear, protective vests and the like or can be mounted on training equipment, such as a heavy bag, striking pad, etc. In a preferred embodiment the transducer is a piezoelectric film which, upon deformation, generates an electrical signal which is indicative of the amount of deformation. By placing the piezoelectric film on top of a deformable material, in a preferred embodiment sandwiching it in the deformable material, impacts to the deformable material will strain the piezoelectric film generating the signal output. In a further embodiement of the present invention, the piezoelectric transducer is mounted on a target pad and provides an analog output indicative of the characteristic of an object impacting the target pad, i.e.

Abstract: A transmitter- receiver of an ultrasonic distance measuring device comprising a cylindrical piezoelectric element made of a polymer in place of a piezoelectric vibrator of a ceramic material or the like which has heretofore been used. The cylindrical piezoelectric element is secured to a columnar supporter in such a manner as to define a chamber in cooperation with a recess which is provided in the peripheral surface of the supporter. The supporter is provided with a pressure equalizing bore which provides communication between the chamber and the outside. In addition, a conical reflector is provided so as to impart directivity to the ultasonic wave transmitted from the piezoelectric element.

Abstract: A piezoelectric load cell which can be utilized for detecting collisions and obstruction of a robot arm end effector includes a force sensing element of metallized polyvinylidene fluoride (PVDF) film. The piezoelectric film sensing element and a resilient support pad are clamped in compression between upper and lower plates. The lower plate has a central recess in its upper face for supporting the support pad and sensing element, while the upper plate has a corresponding central projection formed on its lower face for bearing on the sensing element and support pad. The upper and lower plates are dowelled together for concentric alignment and screwed together. The upper and lower plates are also adapted for mounting between the robot arm wrist and end effector.

Abstract: A film speaker has a film diaphragm for transducing mechanical vibrations into sound waves and a plurality of piezo-electric elements for transducing electrical elements for transducing electrical signals into electrical vibrations. The piezo-electric elements are arranged in first and second grooves of a frame. The first and second edges of the film diaphragm are held between end covers and the frame such that the film diaphragm is coupled to the piezo-electric elements, one portion of V-shaped cross section being coupled to one row of piezo-electric elements and another portion of V-shaped cross section being coupled to the other row of piezo-electric elements.

Abstract: Systems including piezoelectric sensor elements advantageously mounted between supporting hard plastic material of various types or other mechanically similar materials. The sensor can further be supported by backup plate structures. Some backup plates show full shoe coverage and others show partial sole coverage. Detachable mounting formed by mechanically interengaging parts allow transducer inserts to be made in a modular manner for use in different sensor shoes or sensor insole pads, thus allowing many more patients to be analyzed and treated through use of the invention. Also disclosed is a digital charge signal integrator circuit.

Abstract: A hydrophone is provided having at least one flexible piezoelectric sensitive element applied to a support, each sensitive element being formed of a flexible piezoelectric film associated with two electrodes and is applied to a synthetic plastic material support one face at least of which has hollow parts of very different shapes, for example an homogeneous distribution of cups, honeycombs, holes, etc, whose dimensions are determined as a function of the mechanical characteristics of the films used. The stresses applied thereto result in deforming each film inwardly of the hollow parts, which very greatly increases the sensitivity.

Abstract: A piezoelectric polymer (PVDF) hydrophone array consists of multiple layers disposed symmetrically about a stiffener layer. The stiffener layer prevents flexural modes in the operating frequency band and provides a mounting structure for acceleration noise cancellation. The piezoelectric polymer layers are attached to the stiffener layer either directly or through intervening layers which provide mechanical vibration isolation of the polymer and stiffener layers.

Abstract: A sensor for acoustic shockwave pulses, such as in lithotripsy, includes a piezo-electric measuring membrane disposed between two coupling membranes. The intervening space between the coupling membranes is filled with a coupling medium for transmitting the acoustic shockwave pulses. The measuring membrane is in a defined condition largely independent of external influences so that flows in the coupling medium or different pressure exertions on the two coupling membranes do not influence the measured signal produced by the measuring membrane.

Abstract: In an ultrasonic probe produced by forming stripe electrodes on a piezoelectric composite material consisting of a plurality of piezoelectric ceramic rods buried in an organic material, the gaps between the stripe electrodes in the direction of disposition are expanded as much as possible while the gaps of the piezoelectric ceramic rods or their width in the direction of disposition is reduced as much as possible. When the width of the piezoelectric ceramic rod is reduced in the manner described above, the width of the piezoelectric ceramic rod is expanded in a direction orthogonal to the direction of disposition or the gaps of the piezoelectric ceramic rods in that direction is reduced in order to reduce crosstalk and to improve flexibility and sensitivity.

Abstract: An ultrasonic transducer includes a piezoelectric body having a reflector and an acoustic matching layer deposited on the opposing surfaces thereof. The piezoelectric body is constituted by a piezoelectric member exhibiting an acoustic impedence of from 2.5.times.10.sup.6 to 15.times.10.sup.6 kg/m.sup.2 s, and the reflector has a thickness of less than .lambda..sub.2 / 4, where .lambda..sub.2 represents the wavelength of sound in the reflector at a frequency which is one half the free resonance frequency of the piezoelectric body. The acoustic matching layer includes a material exhibiting an acoustic impedance of from 1.6.times.10.sup.6 to 4.times.10.sup.6 kg/m.sup.2 s and has a thickness of from .lambda..sub.3 /8 to 28 .lambda..sub.3 /120, where .lambda..sub.3 represents the wavelength of sound in the acoustic matching layer at a frequency which is one half the free resonance frequency of the piezoelectric body.

Abstract: A pressure sensing transducer comprises a central region which comprises a potting material and which is surrounded by a helix of piezo electric coaxial cable. The transducer includes a barrier that suppresses transmission of external pressure variations to the central region. In addition, the overall radial stiffness of the potting material and barrier is sufficiently low that the electrical signal generated by the coaxial cable have a d.sub.31 polarity (corresponding to axial stretching and contracting of the cable).

Abstract: A robot gripper control system is disclosed which uses PVDF piezoelectric sensors to actively damp exerted force. Instead of charge amplifying the output of the piezoelectric transducer, the output voltage is measured as the charge drains across a path of low resistance. Thus, the sensor output is proportional to the rate-of-force exerted by the gripper. The PVDF sensor and a strain gauge are arranged in a proportional and derivative (PD) control system for the control of force of a robot manipulator hand. Experimental results for the particular disclosed gripper indicate that as much as a 900% improvement in force step response rise time and a 300% reduction in overshoot are possible through the use of the PVDF sensor.

Abstract: An acoustically transparent voided, polyvinylidene fluoride (PVDF) hydrope made of material whose impedance matches the characteristic acoustic impedance (.rho.c) of sea water, having drastically reduced diffraction and resonance effects. The frequency response is thus flat at frequencies less than one-half elastic wavelength in the PVDF material. An array of such hydrophones in front of a projector saves space without affecting projector performance.

Abstract: A dark field ultrasonic transducer is constructed with an outer annular spherical or conical transducer element and an inner spherical element. The outer annular element is excited and insonifies a small portion of a part surface near a discontinuity or crack with longitudinal waves or with surface waves. The inner dark field element is not focused to be sensitive to either reflected sound or waves reradiated from the surface waves, but detects sound scattered from surface discontinuities such as a crack edge. When surface waves strike a crack edge and restrike it after reflection from the bottom of the crack, two pulses are received and the time delay between them is a measure of crack depth. The crack shape and crack depth profile are determined as the part is scanned. A sphere-cone transducer, the preferred embodiment, is fabricated by stretching thin piezoelectric polymer film over a tool having a ball embedded in a conical surface.

Abstract: A method is described for making an electroconductive composite sheet electrode which is conformable and in which a slit-and-expanded or perforated nickel screen is embedded by heat and pressure, so that electrical leads can be easily and strongly attached to the nickel screen before or after integrally bonding a electroconductive sheet electrode to each side of at least one adjacent piezoelectric ceramic/polymer composite sheet electrode which is non-conductive. After poling, the resultant transducer has an increased combined transverse stiffness which increases the hydrostatic voltage coefficient, g.sub.h, as well as the overall hydrophone Figure of Merit.

Abstract: A polymer piezoelectric film comprising a poled film of a vinylidene fluoride copolymer having a high molecular weight as defined by an inherent viscosity within a specific range comprising 40 to 90 mol. % of vinylidene fluoride and 10 to 60 mol. % of trifluoroethylene. Such a high molecular weight vinylidene fluoride copolymer can give a preferable state of molecular arrangement during film formation, particularly preferably formation by casting, to provide a film excellent in piezoelectric characteristic and secondary processing characteristic.

Abstract: The ultrasound sensor (2) of the invention comprises a polymer foil (4) which is supported in its outer region and is piezoelectrically activated at least in one portion (42). The portion (42) is coupled electrically to a first electrode (200) in the form of an adjacent, i.e., touching pin. A second electrode (8), in the form of a grid (214) connected to ground and/or a ring (216) connected to ground, is physically separated from the activated portion (42). The pin (200) is connected to the first input of an amplifier (210). The second input thereof is connected to ground. The metallic take-off at the activated zone (42) results in high sensitivity of the ultra-sound sensor (2) which is provided particularly for the measurement of shock waves with a high pressure amplitude and which finds application in lithotripsy.

Abstract: An ultrasonic transducer for coupling ultrasonic energy to a web-like porous sample includes a sample-contacting layer of soft neoprene, 5-15 durometer hardness, which conforms to the surface of the sample being tested when pressed thereagainst. A non-polarized backing layer of polyvinylidene fluoride eliminates reflections at the end of the transducer remote from the sample. A polystyrene impedance-matching layer is located between the sample-contacting and the backing layer to provide a low-loss, low-impedance coupling of ultrasonic energy to the sample-contactiong layer. A stack of two, and preferably four, metallized polyvinylidene fluoride films is located between the impedance-matching layer and the backing layer. The outer surfaces of the stack are grounded, while the inner surfaces are energized by the ultrasonic energy source. The outer layers are polarized in a first direction, opposite that of the polarization direction of the middle layer.

Abstract: A pressure wave sensor device is provided including at least two sensitive flexible piezoelectric elements wound in two helices in opposite directions of a tubular support and a method for manufacturing same, said device including a copper conducting ribbon wound helically between the two windings of opposite direction and in the same direction as the underlying winding so as to avoid short circuits at the crossing points of the turns and to improve the electric and mechanical couplings between the two sensitive elements, said tubular support being provided with collector assemblies at regular intervals and wound over the whole of its length with the sensitive elements and the conducting ribbon, the different windings then being cut to the right length at the level of the collector assemblies and connected electrically thereto.

Abstract: The invention concerns an ultrasonic transducer for the determination of the acoustic power of an ultrasonic field (1) focused at a point (F). According to the invention, an ultrasonic transducer 2 contains a support structure (4) which has the shape of a spherical cup and whose center coincides with the focus (F) of the focused ultrasonic field (1), and a piezoelectric polymer foil (6) equipped on its respective surfaces (62, 64) with a conductive layer (8) is attached to said support structure. These measures ensure that the acoustic charge vibrations within the area formed by the piezoelectric polymer foil (6) are at least approximately in phase and that the respective surface charge vibrations can be measured with the aid of a single, continuous electrode without partial mutual cancellation.

Abstract: Disclosed is a device for generating an analog output signal indicative of an impact to a transducer. The transducer may be mounted on protective equipment utilized in various martial arts fields, such as protective vests and the like or can be mounted on training equipment, such as a heavy bag, striking pad, etc. In a preferred embodiment the transducer is a piezoelectrical signal which is indicative of the amount of deformation. By placing the piezoelectric film on top of a deformable material, in a preferred embodiment sandwiching it in the deformable material, impacts to the deformable material will strain the piezoelectric film generating the signal output. In a further embodiment of the present invention, the piezoelectric transducer is mounted on a target pad and provides an analog output indicative of the characteristics of an object impacting the target pad.

Abstract: A miniature hydrophone is disclosed which contains a piezoelectric foil as a base element (2) with a linear arrangement of multiplicity of detector elements (10). In accordance with the invention, the electrodes (5) are arranged on a top surface (15) of one of the flat sides of a support (16) and are capacitively coupled by a bonding layer (6) to the base element (2). The detector elements (10) are associated with an amplifier (32) which, with equal length connecting leads (11, 26 and/or 12, 27), is fastened to a side face of the support (16). The electrical interconnection between the detector element (10) and the associated amplifier (32) employs a groove (24) through the corners of support 16. Additional such modules can form an assembly unit in a row arrangement of a size equal to that of the detector elements (10).

Abstract: An optical effect is produced in cooperation with the normal use of an article of manufacture, e.g., a toy such as a frisbee or a ball, or an article of clothing, such as a shoe, by mounting on the article a piezoelectric element for generating electrical energy in response to movement of the article and an optical effect device, such as a neon bulb, gas plasma, liquid crystal, or electroluminescent device, electrically connected to and energized by the element in response to such movement. In one embodiment, the element and device each comprises a thin, layer-like structure, the element and device structures being laminated or attached together.

Abstract: A system is provided for determining the pressure exerted on an object passed between two rollers. The system comprises a sensor of pressure-sensitive material and a transmission/receiving device for generating an ultrasonic wave in the sensor and then detecting the reflected pulse received by the sensor. The time difference between the transmission pulse and the pulse received by the sensor is related to the pressure exerted on the object in the nip. Preferably, the sensor consists of a laminated film comprising in sequence: a first layer of electrically conducting material; a layer of polyvinylidene fluoride; a second layer of electrically conducting material having detector regions; a layer of dielectric material; and a third layer of electrically conducting material.

Abstract: The composite transducer of this invention comprises a prior art longitudinal vibrator-type transducer for transmission of energy and a piezoelectric polymer hydrophone attached to the radiating face of the transducer for the receiving function. During transmission the receiver transducer is short-circuited, and during reception the transmitter transducer is terminated in an electrical impedance that optimizes receiver response and minimizes transducer self-noise. The frequency response of the polymer hydrophone is relatively flat and extends over a much greater frequency range than the transducer.

Abstract: The invention concerns an ultrasonic sensor (24) in which a polymer foil (4) supported in its peripheral area is piezoelectrically activated at least in a partial section (42). The partial section (42) is electrically coupled to electrodes (8). According to the invention, the electrodes (8), which produce an electrical signal in cooperation with this partial section (42) in response to an ultrasonic wave and are spatially separated from the piezoelectrically active section (42). Because of this feature, the ultrasonic sensor (24) can be used also for measuring ultrasonic shock waves with a high pressure amplitude, since an electrically conductive layer for receiving the electrical signal located on the flat sides of the polymer foil (4) in the piezoelectrically active section (42), is no longer needed.

Abstract: Piezoelectric polymer film transducers include a metallized film electrode deposited on each of the two surfaces of the film. The electrodes are provided with leads extending therefrom in staggered parallel relationship. Each lead of the improved connector is associated with a reinforced assembly comprising plastic strips, a terminal connector, optional spacer washers, and a metal rivet penetrating the assembly such that electrical contact is effected between the lead and terminal connector. To insure positive electrical contact, a conductive ink may be deposited on one of the plastic strips through which an orifice is provided. The orifice communicates with a selected lead. The ink coats walls of the orifice to insure electrical continuity between the lead and terminal connector. A modified connector assembly disposes the reinforced connectors beyond the edges of a substrate which carries or supports the piezoelectric polymer film transducers.

Abstract: A piezoelectric transducer comprising a casing having an opening in one face and a piezoelectric element extending across the opening has a casing containing a backing material in direct contact with the piezoelectric element. The backing material comprises a polymeric composition which may contain a heavy metal oxide, e.g. BiO, or a metal, e.g. Ni, in particulate form, and/or may contain particles of a material of lower specific gravity than the surrounding composition, the distribution of said particles being such that they are most concentrated in a region remote from the piezoelectric element and are least concentrated or essentially absent in the region immediately adjacent the piezoelectric element.

Abstract: An oscillator utilizes a piezo-electric transducer as a frequency determining element. The transducer, when unloaded, has a resonant frequency which determines the oscillation frequency and exhibits a predetermined level of amplitude excursion. The transducer, when moved into engagement with a conduit through which fluid flows, becomes loaded and exhibits a change of resonant frequency, whereby the oscillator frequency changes, and also exhibits a change in level of amplitude excursion. The amount of oscillator frequency change and the change in excursion level have respective values when the fluid flowing in the conduit past the transducer is bubble free which differ from the respective values when the fluid contains bubbles. Circuitry responsive to at least one of the changing frequency and amplitude values produces a signal when a selected one of the bubble free and bubble containing conditions is detected.

Abstract: An ultrasonic transducer includes a piezoelectric polymer film folded as at least two layers and having electrodes on both the surfaces thereof. The ultrasonic transducer is responsive to a signal, applied across electrodes, to produce an ultrasonic wave to be focused at one spot so that it is converted to an electric signal. In this ultrasonic transducer, a groove or through holes are formed on and along the folded area of the piezoelectric polymer film.

Abstract: An impact sensing arrangement comprises a pair of bodies that are separated from each other and arranged so that an impact on one of the bodies will cause it to move toward the other body, and an elongate piezoelectric pressure sensing element that is positioned between the bodies, the pressure sensing element being mechanically coupled to each of the bodies over at least one quarter and preferably at least two thirds, the width of the sensing element.The arrangement is particularly suitable for use in an ordance projectile in which case the sensing element 10 may extend in a loop around the projectile between the nose 3 and body 2 of the projectile.

Abstract: A sensor for generating a signal in response of a variation at the tactile face. The sensor comprises superposed transmitting and receiving layers, which are provided with electrodes for the supply and pick-up of electrical signals to the transmitting layer and from the receiving layer respectively. With a high acoustic impedance of the boundary medium adjacent to the transmitting layer and a low acoustic impedance of the boundary medium adjacent to the receiving layer or vice versa, the sum of the thicknesses of the transmitting and receiving layers is an odd number of v/4f. With similar impedances, either low or high, of the said boundary media the aforesaid sum is an even number of v/4f. v is the propagation velocity of the acoustic vibration in the material of the transmitting and receiving layers and f the frequency of the signal supplied.

Abstract: An ultrasonic transducer includes a plate-shaped piezoelectric body made of a piezoelectric polymer material and having a polarized portion obtained by polarizing a prescribed region thereof, as well as first and second unpolarized portions contiguous to the polarized portion. A first electrode is formed on one main surface of the piezoelectric body to cover the polarized portion and has an edge portion extending over the first unpolarized portion. A second electrode is formed on the other main surface of the piezoelectric body to cover the polarized portion and has an edge portion extending over the second unpolarized portion. A first conductive lead is electrically connected to the edge portion of the first electrode, and a second conductive lead is electrically connected to the edge portion of the second electrode.

Abstract: A transducer for effecting conversion between stress wave energy and electrical energy comprising a plurality of individual electrically conductive electrode elements presenting an array of coplanar electrode element faces, an overlying sheet of dielectric material carrying an electrically conductive film or coating on its side remote from the individual electrode elements and which is common to the individual electrode elements, means for supporting the sheet peripherally to lie freely on, but in tension over, the coplanar faces of the individual electrode elements, adjacent areas of which are spaced from each other by gaps which are sufficiently large compared with the thickness of the sheet to avoid or minimize shear stress transmission between adjacent areas of the sheet overlying respective adjacent individual electrode elements.

Abstract: A hydrophone comprising a tubular thin-walled member of a piezoelectric polymer such as polyvinylidene with electrodes covering the interior and exterior surfaces of the tubular member. An elastomeric core is inserted into the interior of the tubular member and then brought into radial compression against the interior surface of the tubular member.