Abstract: For fastening and connecting tubular piezoelectric driving elements in the write heads of ink writing devices, contact clips are provided, arranged on a circuit board, and presented connector banks, into which the piezoelectric driving elements can be snapped. Several circuit boards can be plugged into a mother board. The mother board, equipped with circuit boards and connectors which are wave-soldered to the mother board constitute a piezo-tubular bundle.

Abstract: In a device of the type of an Inchworm Translator as called by Burleigh Instruments, Inc., N.Y., an electromechanical driver for a shaft of the device comprises a plurality of electrostrictive layers stacked longitudinally of the driver with internal electrodes interposed. Preferably, each gripper or clamper for the shaft is of a like structure and comprises a pair of external electrodes on an outer peripheral surface thereof. More preferably, the gripper comprises either an electrically insulating and abrasion resistive or an electrically insulating and vibration damping film which defines a cylindrical inner peripheral surface of the gripper. The film is preferably divided into a plurality of film portions. The electrostrictive layers are preferably of a composition of a formula of (1-x)Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3.xPbTiO.sub.3 where x is about 0.35. The electrically insulating and abrasion resistive film may be of either a plastic or a ceramic material.

Abstract: Improvement of resonator circuit parameters, unwanted mode suppression, and the frequency-temperature characteristic of a crystal resonator is provided by a doubly cut crystal resonator plane having at least one major face including a cylindrical contour, the axis of which is parallel to the direction of the projection of the eigenvector (the normal coordinate) for the desired operating mode. The cylinder axis is at an angle to the doubly rotated electrical axis such that the fast shear "b" mode is suppressed while the slow shear "c" mode is unaffected. The radius of the cylinder is selectively chosen for altering the frequency-temperature characteristic.

Abstract: In a pressure transducer of the piezoelectric type, a resonator (10) is made up of a pellet (16) mounted inside an element designed to be subjected to the action of a pressure on its exterior face (18). The pellet (16) and the element (12) are cut in the same quartz block, using a cut which provides two vibration modes. The forces resulting from the external pressure are transmitted to the edge of the pellet (16) by connecting bridges (22, 23) whose orientation is chosen so that one of the vibration modes has maximum sensitivity to the forces while the other mode has a practically zero sensitivity.

Abstract: A temperature-compensated quartz oscillator having a first plate of quartz that carries a first electrode which displays a sensitivity to temperature that exceeds that of the piezoelectric quartz wafer which comprises a first resonator which vibrates at a reference frequency f.sub.M. The first plate cooperates with the first electrode and a third electrode to form a second quartz resonator. Means for applying to the first and third electrodes an excitation electric power to drive the active portion of the first plate according to a mode which is sensitive to temperture, at a frequency f.sub.T close to, but slightly different from, the reference frequency f.sub.M. Means for comparing, which enable comparison of signals at the terminals of the second and third electrodes, and control means for the regulating means for applying an excitation electric power from the active portion of the piezoelectric wafer.

Abstract: A piezo activated liquid supply pump system includes a cylinder shaped vibration pipe made of a piezo element, and a cone shaped pressure chamber surrounded by a rubber wall. The cone shaped pressure chamber is disposed in the cylinder shaped vibration pipe in a manner that a cavity is formed therebetween. Polyethylene glycol is filled in the cavity for transferring the vibration of the piezo element to the rubber wall of the cone shaped pressure chamber. The volume of the pressure chamber varies in response to the vibration of the piezo element to achieve the liquid supply. The cone configuration of the pressure chamber ensures an effective removal of air bubbles from the pressure chamber. The cavity is communicated with a buffer chamber so as to introduce the polyethylene glycol into the buffer chamber when the liquid contained in the pressure chamber freezes, whereby the expansion of the pressure chamber caused by the freezing of the liquid is absorbed.

Abstract: In a piezoelectric transducer (10) an external element (12) of tubular form receives a pressure, notably a pressure to be measured, on its external face (16). It is cut in a quartz crystal in one piece with a plate (25) capable of vibrating under the action of an electric stress and extending in a plane parallel to the longitudinal direction of the tubular element inside the latter. Each of the longitudinal edges of the plate is connected by a transverse connecting element (30, 31) to the internal face (14) of the tubular element so as to transmit forces (F1 and F2) resulting from the application of the external pressure to the plate (25) in a direction substantially parallel to its plane and perpendicular to the axis of the tubular element (12).

Abstract: A sleeve/rod type squeeze bearing system is disclosed in which the piezoceramic driving element is placed in compression to an extent that limits or eliminates stress reversals of the piezoceramic driving element during vibrating cycles. Eliminating or limiting stress reversals increases reliability of the bearing system and extends the useful life of the bearing elements. The bearing load of such a system may also be increased.

Abstract: A valve (10) is provided for the control of fluid flow. The valve (10) includes a housing (20) having a fluid inlet aperture (40) and a fluid outlet aperture (48). A piezoelectric device (12) is disposed within the housing (20) adjacent the fluid inlet aperture (40) and the fluid outlet aperture (48). Structure (52, 54) is provided for applying a voltage to the piezoelectric device (12) for causing motion of the piezoelectric device (12) to thereby establish a path (62) within the housing (20) between the fluid inlet aperture (40) and the fluid outlet aperture (48) to enable fluid to flow through the housing (20).

Abstract: A terminal station for communication with one or more similar remote stations via mains wiring includes a piezo-electric coupler (22) whereby carrier signals are transmitted to and received from the line (24). The coupler is driven by an oscillator (21) modulated in correspondence with an input signal and tuned to the resonant frequency of the coupler.

Abstract: An acoustic transducer with high sensitivity and low resonance frequency is constructed of a cylinder having inner and outer layers rigidly bonded together. At least one layer is a thickness poled piezoelectric material. The cylinderical can be closed by end caps to shift nodal locations.

Abstract: The high-frequency piezoelectric resonator comprises a quartz plate or disk having a region of reduced thickness which forms a diaphragm and is joined to the remainder of the plate or disk by means of a zone forming a step. A conductive electrode extends from the exterior of the disk or plate to the center of the thinned region and is provided with a conductive tongue constituted by a metallic film-layer of controlled thickness and disposed in the stepped zone. The method involves formation of the disk or plate by ion machining whereas the electrodes and the conductive tongue are formed by the sputtering technique.

Abstract: A holder for a piezoelectric crystal wafer comprising a base, a pair of spaced apart leaf springs secured to the base and a seat member secured to the base between the leaf springs. The leaf springs spread outward upon the application of an external force, to permit the placement of a crystal wafer on the seat member and return toward a normal position upon the release of the external force, to resiliently hold the crystal wafer on the seat member.Each leaf spring includes a pair of prongs at the upper end thereof, separated by a slit having a width slightly larger than the thickness of the wafer. An elongated slot is formed in each of the leaf springs and having a width greater than the width of the slit between the prongs. When the crystal wafer is inserted in the holder, the upper part of the wafer is received in the slit of one leaf spring and a side portion of the wafer extends through the slot of the leaf spring.

Abstract: Disclosed is apparatus for providing for increased heat transfer efficiency f a heat exchanger by separating contiguous fluid conductive channels by means of a flexible sheet fabricated from a piezoelectric polymer. An electrode pattern of predetermined configuration is applied to one or both sides of the piezoelectric sheet and an electrical signal applied thereto in order to set the sheet into a flexual resonance condition whereupon a standing wave pattern is established to not only break up the boundary layer of fluid which adheres to each side of the sheet, but also minimizing the thickness of the laminar sub-layer.

Abstract: An ink jet drop-on-demand printing system having gray scale capability comprising a transducer having a plurality of separately actuable sections. Print data is provided which defines a selected drop volume and control means is provided which is operable in response to the print data to produce drive signals to selectively actuate a particular combination of the separately actuable sections of the transducer to produce a drop of the volume specified by the print data. To provide further control over the drop volume while maintaining the drop velocity within selected limits, the amplitude of the drive signals can also be varied. A further refinement can be provided by varying not only the amplitude of the drive signals but also the pulse width of the drive signals. In a first embodiment the transducer sections are of equal length, while the sections are of unequal length in a second embodiment.

Abstract: A piezoelectric actuator comprising a tubular casing and an elongated piezoelectric member disposed in the casing. The piezoelectric member has axially spaced ends, one of which abuts the shoulder of the casing. The piezoelectric member expands and contracts in response to an applied voltage, another end effecting a pumping operation. The piezoelectric member forms first and second longitudinal surfaces extending along substantially the entire length of axis. The piezoelectric member is formed as a lamination of a plurality of piezoelectric plates, to each of which is applied an electrode element on one of lateral surfaces. The electrode elements protrude on the first or second surfaces, alternately. First and second electrode members are located at the first and second surfaces, respectively. The first surface may be a surface of an opening which extends through the piezoelectric member, and the second surface may be a surface of an outer cylindrical surface of the piezoelectric member.

Abstract: A number of piezoelectric discs are stacked with electrodes inbetween for application of DC voltage thereto through a pair of lead wires, forming piezoelectric blocks, and a plurality of the piezoelectric block are stacked to form a moving member, which is inserted in a fixed member, a hollow case of rigid material such as steel; by applying voltages to electrodes of selected piezoelectric blocks, any selected block(s) can be driven either to decrease or increase the diameter and increase or decrease the thickness, thereby fixing selected block(s) to the fixed means or releasing of the fixing can be made freely and individually; and by appropriately combining voltage impressions timings and polarities to individual piezoelectric blocks, motion of the moving member in relation to the fixed member, for instance in a measuring worm-like way, is obtainable.

Abstract: An arrangement is disclosed for piezoelectric resonators utilizing linear and parallel sides or flats located on the periphery and opposite ends of the resonator. These sides are located normal to the axes wherein collinear forces applied to the resonator produce a desired effect upon its natural resonant frequency. For mechanical sensor applications this effect is maximized while for applications requiring a stable frequency or time base this effect is minimized. The outline peripheral shape of the resonators utilizing this mounting arrangement varies in accordance with the crystallographic orientation present in each resonator.

Abstract: The invention is a transducer which acts with an acoustical lens to produce a highly focussed beam and attenuated side lobe waves. The transducer comprises a resistive electrode which attentates electrical signals applied to and emanating from the peripheral region of the transducing element.

Abstract: A quartz crystal vibrator has a vibrator element which includes a quartz crystal plate having obverse and reverse sides. A first excitation electrode is provided on the obverse side of the quartz crystal plate at the central portion thereof, and a first connecting electrode extends radially from the first excitation on the obverse side. A first supporting electrode is connected to the first connecting electrode and is provided fragmentarily along the entire circumference of the quartz crystal plate on the obverse side thereof. A second excitation electrode is provided on the reverse side of the quartz crystal plate at the central portion thereof at a position underlying the first excitation electrode, and a second connecting electrode extends radially from the second excitation electrode on the reverse side.

Abstract: An improved construction for piezoelectric crystal assemblies has significant advantages both from the standpoint of operational attributes of the finished product and of adaptability to being mass produced in an expeditous and economical manner. A related, improved method of making piezoelectric crystal assemblies, including those of the aforementioned improved construction, is also provided, which similarly has significant advantages from the standpoints of speed and economy.

Abstract: Transducer structures for use in volume flow measurements which generate a first uniform beam and a second focused beam within the uniform beam. The transducer may include concentric elements, a linear array, or combinations thereof. In a two element concentric array, a central disc generates a uniform beam and a peripheral annular element having a lens thereon defines a second focused beam within the first beam. In a linear array, a plurality of juxtaposed linear elements define a scan surface, and a segmented element within the linear element array defines a focused reference sample volume within the scanned surface. A concentric array having a plurality of annular elements is driven with amplitude weighting of each element, in accordance with a Fourier-Bessel approximation to the desired beam pattern, thereby electronically achieving ultrasonic beam width control.

Abstract: A contacting device for electrically connecting rows of tubular piezo transducers of a printing head of an ink printing device consisting of a printed circuit board having separate conductor paths, a row of feedthrough holes for each row of transducer elements with one hole for each element, a first contact element having an inside contact sleeve biased against the inside wall of the transducer element and a flexible spacer extending therefrom and through an opening in the board adjacent the feedthrough hole, a second contacting element having a resilient connector supporting a resilient clamp for embracing the outer surface of the element being mounted in another hole adjacent the feedthrough opening with both the elastic spacer and the resilient connector being soldered to the conductor paths so that the element is positioned above the feedthrough hole and an electrical current can be applied to the transducer.

Abstract: Electrical connections to thin film coatings, especially useful in a fluid flowmeter, have a conductive coating pressed against a rigid, relatively long, connector bar by conductively coated pads of elastomeric material at a selected controlled pressure, with the electrical connections to the film coating being made through the bar and pads. Utilizing this method, localized high stress areas which cause damage to the thin film are avoided, and low current densities are accomplished by the controlled contact pressure over a large area of the film coating.

Abstract: Disclosed is apparatus for providing for increased heat transfer efficiency f a heat exchanger by separating contiguous fluid conductive channels by means of a flexible sheet fabricated from a piezoelectric polymer. An electrode pattern of predetermined configuration is applied to one or both sides of the piezoelectric sheet and an electrical signal applied thereto in order to set the sheet into a flexual resonance condition whereupon a standing wave pattern is established to not only break up the boundary layer of fluid which adheres to each side of the sheet, but also minimizing the thickness of the laminar sub-layer.

Abstract: A piezoelectric assembly with a flexible circuit interconnect is provided. The flexible circuit interconnect is comprised of a first flexible insulating base film including spaced electrically conductive circuit traces, a second flexible insulating film disposed over a portion of the first base film and a segment of the traces, and means for electrically connecting the traces to an electrical circuit. Also provided is a method for manufacturing a flexible circuit interconnect for a piezoelectric element comprising laminating spaced circuit traces on a flexible insulating base material to define a contact arrangement with a first set of terminal ends of the traces; attaching termination electrical connectors at a second set of terminal ends of the traces; mounting an insulating overlay to the base material for insulating a portion of the traces and electrical connectors; and, mounting a piezoelectric element to the contact arrangement.

Abstract: An ultrasonic transducer providing a plurality of different focal lengths within a unitary structure and comprising a piezoelectric element having a cylindrical spiral surface with respective sections of the spiral surface providing respective different focal lengths. Each section of the spiral surface can include electrodes in the form of a Fresnel zone pattern to provide focusing in the orthogonal dimension to the spiral axis.

Abstract: A piezoelectric motor of the invention comprises a stator and a rotor one of which includes at least one first piezoelectric oscillator. The rotor consists of a first and a second parts one of which parts includes a second piezoelectric oscillator. Said parts of the rotor are mounted for relative rotation about the axis of rotation. The first part is in contact with the stator along the first surface of frictional interaction and with the second part along the second surface of frictional interaction. Each surface of frictional interaction is formed by rotation of at least one straight line length about the axis of rotation of the rotor.

Abstract: An ink jet comprises an elastic tubular member (14) characterized by piezoelectric properties. The tubular member (14) is terminated in an orifice (26) adapted to pass droplets of ink when the chamber formed within the tubular member (14) is reduced in size. The piezoelectric properties are provided by a substantially homogeneous mixture of piezoelectric material and an elastic binder.

Abstract: Disc shaped quartz crystal resonators of plano-convex, plano-plano, and bnvex configurations have the b-mode resistance raised relative to the c-mode resistance by the proper choice of mounting geometry, thus suppressing the undesired b-mode in precision oscillator circuits without the use of added circuitry.

Abstract: Doubly rotated quartz crystal blanks such as the SC, IT and FC cuts have ir apparent angles of cut and hence their frequency vs. temperature characteristics modified by changing the contours of one or both of the convex sides thereof, or by changing the electrode areas thereof; or a combination of these two changes.

Abstract: A driving electrode on a surface of the piezoelectric vibrator in accordance with the present invention has a blank which is narrow at the center portion and wide at the right and left portions on the Z axis. And the driving electrode is the shape easy to operate in the fundamental main vibration, and hard to operate in the spurious vibration. Thus the piezoelectric vibrator operates efficiently in the fundamental main vibration.

Abstract: In an ink jet printing apparatus an ultrasonic transducer is an elongated cylindrical assembly submerged in the ink which is held under pressure in an ink chamber. To provide an array of ink jet filaments having uniform length and uniform drop formation, the acoustic energy of the transducer is focused by the internal wall of the ink chamber toward an ink jet array on an orifice plate. The said invention also generates ink droplets from all jets at the same phase--which simplifies the driving electronics of the array for high resolution printing. In one embodiment the internal chamber wall, in cross-section, is a sector of an ellipse and in another embodiment it is a parabola.

Abstract: An ultrasonic wave transducer is formed from a body of piezoelectric material having nonuniform thickness. Each location on the transducer is resonant at a different frequency according to the thickness at that point. By changing the frequency of the applied excitation signal, the origin and direction of the radiation can be altered.

Abstract: A piezoelectric tubular monopole element with zero end displacement which s an omnidirectional sensitivity over the widest possible frequency range. The center section is radially or thickness-poled and the end sections are longitudinally or length-poled. The positive electrodes are connected in parallel and the negative electrodes are connected in parallel for electrical parallel output.

Abstract: A deflection arrangement is described which comprises several piezocrystal elements which are separately driven by a positive or a negative voltage. In this configuration, there is no elastic hysteresis. The arrangement is particularly suitable for automatic focusing systems.

Abstract: A piezoelectric bi-resonator with electrodes not adhering to the crystal, comprising at least first and second plates in dielectric material on which plates are deposited respectively first and second electrodes, a third plate in dielectric material having faces opposed to the first and second plates respectively, on which faces are respectively deposited third and fourth electrodes, connected together, and a piezoelectric body constituted by two piezoelectric chips made of quartz, independent and similar, one of which is interposed between the said first and third electrodes, without contact therewith, and the other is interposed between the second and fourth electrodes without contact therewith, the said piezoelectric quartz chips being arranged so that their axes Y' are opposite.

Abstract: In an exemplary embodiment, transducer combs for ultrasonic arrays or compound scanners, which consist of a specifiable number of transducer elements, are produced by a technically particularly simple and cost-saving manufacturing process, with the following method steps:(a) a plurality of thin strips of transducer element material, in particular, piezo-material, are combined by cohesive bonding into a stack; e.g. on the basis of alternate interpositioning of spacing strips or on the basis of application of spacer beads on the transducer strips of piezoelectric material,(b) from the stack thus formed, individual packets are cut off transversely to the transducer strips,(c) each individual packet is completed as a transducer comb by itself.

Abstract: An ink jet tip assembly in which the individual jets are comprised of a piezoelectric cylinder having a longitudinally through bore, a glass ink nozzle disposed in the cylinder bore and a low melting temperature alloy interposed between the bore and the nozzle for anchoring the nozzle to the piezoelectric cylinder. The method of assembly for the individual jet tip assemblies comprises inserting the glass ink nozzle into the cylinder bore which contains the anchoring alloy in a molten form. A method of checking for flaws in the cylinder comprises fluxing the cylinder bore for allowing flux to pass through any cylinder pinholes or cracks. Upon introducing solder for coating the interior cylinder wall, some solder will appear as shining spots or areas on the cylinder exterior wall.

Abstract: A rotary magnetic head apparatus having a bending mode vibrator or vibrators mounted on a rotary cylinder, the vibrator comprising either ring shape piezoelectric vibrators bonded together with their polarization axes aligned in the direction of the thickness or the bonded piezoelectric vibrators bisected along a diameter of the ring, the bending vibrator mounting thereon a magnetic head or heads.

Abstract: The present invention provides a piezoelectric transducer and pickup means using the same for electrical string instruments, the transducer comprising a long and flat outer layer of flexible material and a flexible piezoelectric cable which is buried therein and has a center electrode, a piezoelectric layer formed on the outer periphery of the said electrode and an outer electrode formed on the outer periphery of the said layer, the stiffness thereof being enhanced by either using elastomer of the hardness of more than 80 as measured by the Spring Hardness Test Method in the Physical Testing Method for Vulcanizing Rubber of Japanese Industrial Standard (JIS K 6301) as the material for the outer layer, or by plaiting (braiding) metal wires or by winding the outer electrode of the piezoelectric cable in such a manner as to enable it to press against the piezoelectric layer.

Abstract: A thickness-shear mode piezo-electric vibrator comprises a piezo-electric crystal operable in the thickness-shear mode, driving electrodes formed on opposed surfaces of the crystal, and an addition mass formed on at least one of the driving electrodes and positioned on the nodal line of a 3-fold harmonic vibration so that the frequency f.sub.o of the fundamental main vibration and the frequency f.sub.3s of the 3-fold harmonic vibration always satisfy the following relation within the practical application ranges of temperature and load capacitance; ##EQU1## thereby effectively eliminating or preventing the "abnormal frequency phenomenon" which would otherwise occur due to the 3-fold harmonic vibrations.

Abstract: A flexible, composite, acoustical energy transducer made from ferroelectric, piezoelectric, and/or electrostrictive materials in combination with a polymer, such as silicone or polyvinylidene fluoride (PVF.sub.2), preferably having electroelastic properties. The materials are formed into platelets or wafers which have electrodes on their facial surfaces and are arranged within the polymer with each wafer in the same x-y plane such that their polarizations are in the same direction and perpendicular to the x-y plane. The wafers are aligned in directed rows, spaced from each other and are totally encased within the polymer. Thin conductive sheet or foil electrodes are secured to the upper and lower faces of the polymer and a conductive material between each wafer and the foil electrically connects the wafers to the foil electrodes. To protect the electrodes and prevent electrical shorting, a rubber coating or any other suitable insulator may be applied to the outside of the electrodes.

Abstract: A cylindrical tubular piezo-electric actuating element for recording heads, particularly in mosaic-type recording equipment in which a recording ink or fluid, contained in a compression chamber surrounded by the cylindrical actuating element, is forced out in droplets by piezo-electric constriction of the actuating element, the latter having dimensions which are such that the quotient derived from the wall thickness and the arithmetic mean of the internal and external diameters of the element matches the Poisson number (.mu.) of the piezo-electric material employed, whereby maximum constriction of the internal diameter is effected with no change in the external diameter of the actuating element.

Abstract: Piezoelectric resonator comprising a sealed box in which a vacuum has been formed or into which has been introduced a residual gas, within said box a piezoelectric crystal having first and second main opposite faces, a first metal electrode deposited on the first main face of the crystal and a second metal electrode deposited on the second main and opposite faces of the crystal, a first conductor connected to the first electrode and extending outside the box, a second conductor connected to the second electrode and extending outside the box and means for maintaining the crystal within the box, wherein the piezoelectric crystal comprises a central portion and a peripheral portion forming a ring which spacedly surrounds the central portion and connected to said central portion by an intermediate portion which over at least part of the distance between the central portion and the peripheral portion has a reduced thickness compared with the thickness of said central and peripheral portions wherein the first and s

Abstract: An electromechanical transducer is made from a member providing for the introduction of electrical energy and the conversion of such energy to mechanical vibrations radially. First means cooperate with the transducer member in limiting the vibrations of the member in a direction for radially contracting the member. When the transducer member has a narrow gap extending along the length of the transducer member, the first means includes a resilient member having a width greater than the width of the gap and disposed in the gap to prestress the transducer member and prevent the ends of the gap from contacting each other during such vibrations. Second means cooperate with the transducer member for limiting the vibrations of the member in a direction for radially expanding the member. The second means include at least one band extending circumferentially around the transducer member for limiting the mechanical vibrations of the member in a direction for expanding the member.

Abstract: A beam of ultrasonic energy is scanned through the use of a steerable mirror positioned in a liquid path traversed by the beam between a transmit-receive crystal and the target. The mirror is comprised of a material selected to have an angle of excitation of surface waves at the liquid-mirror interface which lies outside the range of angles of transmission and reception incidence at which the beam impinges on the mirror.

Abstract: In the use of a resonator as an overtone crystal of an aperiodic oscillator circuit without additional selection means, by dimensioning of the resonator itself and its electrodes, suppression particularly of the fifth harmonic during operation of the resonator with the third harmonic is improved by means of special resonator dimensions.

Abstract: A piezoelectric crystal has a concave active surface and a high acoustical impedance. A flat layer of molded material having a low acoustical impedance faces the active surface of the crystal to form a space therebetween. An intermediate layer of molded material having an intermediate acoustical impedance fills the space between the crystal and the flat layer. Preferably, the intermediate material has a sonic velocity near that of water, and the flat layer has a uniform thickness of approximately 1/4 of the average wavelength of the ultrasonic energy emitted by the crystal. A housing supports the crystal, the flat layer, and the intermediate layer.

Abstract: A transceiver capable of transmitting and receiving ultrasonic signals for liquid level gauging, the elapsed time between the transmission of a pulse and the reception of an echo pulse reflected from the surface of the liquid being measured to afford an index of the level of the liquid. The transponder is constituted by a piezoelectric transducer assembly suspended within an open-ended casing by an electrically non-conductive elastomeric material which serves to rapidly damp the vibratory activity of the transducer to prevent ringing thereof which interferes with reception. In the assembly, the piezoelectric transducer is sandwiched between a loading plate and a horn-shaped radiating plate, the assembly being held together by a bolt which extends between the plates and passes through the transducer. The transducer operates in the compression mode and is therefore capable of operating reliably with a high voltage drive signal to cause the radiating plate to emit an ultrasonic beam having a narrow angle.