Abstract: An elastomer support for a sonar transducer includes a ceramic stack electromechanical driver, a pair of rigid support members, and a pair of elastomer layers disposed between the ceramic stack electromechanical driver and the support members. The elastomer support provides effective mechanical stress reduction in the ceramic stack driver, as well as, a simple, reliable heat dissipation means for the transducer.

Abstract: The metal-ceramic actuator includes an electroactive substrate having at least a pair of opposed planar surfaces and a determined thickness, with the ceramic substrate being poled in its thickness dimension. Conductive electrodes sandwich the ceramic substrate and are bonded to its planar surfaces. Metal caps, each having a concave cavity bounded by a rim, are bonded to both planar surfaces of the ceramic substrate. A potential is applied to the conductive electrodes to cause an expansion of the ceramic substrate in its thickness dimension and a concomitant contraction in its planar dimensions. The contraction creates a flexure of the metal caps, which flexures are used to actuate another instrumentality.

Abstract: A compliant cover for use with acoustic source transducers includes a rubber boot bonded to a shell of the transducer. The cover has a groove molded within a surface thereof to allow the shell to expand and contract with reduced resistance. Conventional transducers having rigidly mounted covers disposed on the shell which resist the motion of the shell and decrease the overall efficiency of the transducer.

Abstract: A transducer includes an acoustic radiating member for generating acoustic energy in a transmitting medium and a driver member that is pivotally connected to the radiating member. The driver member is for urging movement of the radiating member, wherein such movement generates the energy. Pivoting of the driver member with respect to the radiating member relieves predetermined stress in the driver member. The radiating member may include, for example, a flat element such as a bar, plate or disk, or an I-shaped element. The driver element may include an electroactive material. The driver element may be connected to the radiating element by support apparatus that is fixedly coupled to the radiating element includes a screw having a predeterminedly contoured end that engages a complimentarily contoured recess connected to the driver element for permitting the pivoting. When the support apparatus includes a screw it may be adjusted for supplying a predetermined force on the driver element.

Abstract: A composite split cylinder transducer comprises an electromechanical driver and a cylindrical shell having a longitudinal gap. The shell further has a portion, disposed opposite the gap, comprised of a high strength material having increased stiffness. Transducers of this configuration are capable of being employed at greater ocean depths where high hydrostatic pressure conditions exist with little effect on acoustic performance.

Abstract: A broadband electroacoustic transducer is disclosed which provides an improved response over a relatively broad range of frequencies. The transducer includes a plurality of tines extending between the outer circumferential surfaces of a pair of piezoelectric cylinders. The cylinders are disposed about a common axis and are separated by a gap. The tines extend longitudinally across the gap from one cylinder to the other. Each tine is separated from the adjacent tines by a space which is sized to prevent contact between the tines when the cylinders radially oscillate. A pre-stress wrap is disposed over the tines on both sides of the gap to provide a static, inwardly radial force on the cylinders.

Abstract: A bonded insulator flexural transducer for use in sonar applications includes a hollow metal tube having an inner surface, a segmented ceramic electromechanical driver disposed along an inner surface of the tube and a bonded insulator disposed between the segmented driver and the metal tube. The bonded insulator includes a high dielectric strength film, a layer of a binding fiber material, and a layer of epoxy. The dielectric film provides the electrical isolation between the driver and the shell and the binding fiber material provides a reliable bond by effectively trapping the epoxy between the driver and shell.

Abstract: A reception system including a central core (5) formed of a traction cable (6) and a harness (7) of conducting wires. A fibrous or porous acoustic screen (8) made, for example, from a fibrous or porous material is formed around the core. Sensitive elements are arranged outside this screen, with discontinuous inner electrodes (9) connected to the different wires of the central harness (7), and a common outer electrode (13). A pipe made of a piezoelectric material (12) is formed therebetween. The whole is covered with a protective sheath (2). With such a multi-layered sensitive structure, the manufacturing process of the reception system can be simplified.

Abstract: A radially-polarized piezoelectric cylindrical transducer is provided. The ransducer has an electrically conductive end cap affixed with a conductive epoxy to one end of a piezoelectric body and a second cap affixed to the other end. The piezoelectric body comprises a layer of piezoelectric material located between an inner and an outer electrode. The outer electrode has an electrode gap which electrically insulates the end cap from the outer electrode. The unit is electrically conductive and permits the attachment of two electrical leads to its exterior, one to the first end cap and the other to the outer electrode of the piezoelectric body. In an alternative embodiment, two conductive end caps are affixed with conductive epoxy to opposite ends of the piezoelectric body. In this embodiment, the inner electrode has an electrode gap which electrically insulates the second end cap from the inner electrode. One electrical lead attaches to each end cap in this alternative embodiment.

Abstract: A solid-state tunable transducer has been developed by incorporating an elastically nonlinear material, silicone rubber, into an electroacoustic transducer made from piezoelectric ceramics. The resonant frequency and mechanical Q of the transducer are tuned mechanically by applying a uniaxial compressive stress to the composite. The resonant frequency is tuned electrically by placing a piezoelectric actuator into the composite and varying the magnitude of the d.c. bias.

Abstract: This invention concerns a low frequency, high energy output electroacoustic transducer. It utilizes a vibratory unit formed of a stack of hollow ceramic cylinders about which is fitted a resilient metal sleeve. The metal sleeve is tensioned outwardly during assembly of the unit so that, upon relaxation, it will fit about the stack as tightly as possible. To further make the stack and sleeve integral, a bonding material is placed between the two. A gap in the sleeve serves as a cutting guide for gapping the stack. Air backing is used to further increase the energy output of the transducer.

Abstract: An electro-acoustic transducer comprises two transducer units each having first and second ends, a tubular supporting member disposed between the two transducer units, and a pair of oppositely disposed supporting components between which the transducer units and tubular member are disposed. One of the transducer units is compressively clamped between one of the supporting components and one end of the tubular member, and the other of the transducer elements is compressively clamped between the other of the supporting components and the other end of the tubular member.

Abstract: A support member preferably made of a metal such as cold rolled steel is disposed in a looped configuration and is provided with a gap. A transducer member preferably made of a piezoelectric material such as a ceramic is disposed within the support member. The transducer member is provided with a gap at a position corresponding to the gap in the support member. A closure member made from a suitable springlike material such as an alloy steel is attached to the opposite ends of the support member at the position of the gap as by welding. The closure member extends in a U-shaped configuration into the looped configuration (in section) defined by the support member and the ceramic member. The axial length of the closure member defines the bandwidth of the frequency vibrations generated by the transducer member.

Abstract: A split-ring or split-cylinder transducer in which a full or partial boot covering a shell is caused to be looped into the gap of the shell so that outward radial movement and circumferential expansion of the shell causes the boot to also move outwardly thus reinforcing the sound wave generated exterior to the shell of the transducer.

Abstract: The sonar transducer includes a metal core about which is situated a cylindrical piezoelectric ceramic ring element with paper interposed therebetween. In order to improve resistance to fracture resulting from mechanical shock, in one embodiment, the core is reduced in diameter, such that a potting compound can be situated between the paper and the ring. In a second embodiment, the ring element is divided into two individual, axially aligned cylindrical ring subelements with a gasket interposed therebetween.

Abstract: An electroacoustic transducer according to the invention comprises a stacking of annular plates (13) made of piezoelectric ceramics alternating with annular electrodes (14) and pressed by an axial prestressing stem (15). The contact faces between each plate and the adjacent ones are made of two flat parts (16a, 16b) whose surface is smaller than the maximum cross section, due to the chamfers (19a, 19b, 20a, 20b) which truncate the edges of each plate. One application is the construction of low frequency sonar transmitters. Referenced elements refer to FIG. 3.

Abstract: A monopole transmitter for a sonic well tool includes an axial tube, a piezoceramic cylinder surrounding the axial tube, an endcap disposed at each end of and firmly contacting the cylinder, and an apparatus for holding the endcaps firmly against the axial tube. The endcaps firmly contact the axial tube without simultaneously contacting an upper bulkhead. The apparatus may include spring washers disposed between the bulkhead and at least one endcap, or it may include a spring disposed between a nodal mount and each endcap. A nodal mounting tube may be disposed around the axial tube, a ring being disposed at each end of the nodal mounting tube, each ring being disposed outside of the cylinder, the apparatus including a spring disposed between each ring and an endcap outside of the cylinder for biasing the endcaps in tension against a ring thereby holding each endcap firmly in contact against the axial tube.

Abstract: A transducer assembly includes a hollow support member disposed in a looped configuration and having an axial opening. A hollow transducer supported within the support member may be made from a piezoelectric material and may be provided with an axial opening corresponding to position to the axial opening in the support member. In one embodiment, the outer surface of the support member may be thinned at spaced positions as by sockets or spaced axial grooves extending partially through the support member. The support member may be thinned at strategic positions to control the vibrational frequency and the frequency bandwidth of the transducer assembly. The thinned portions of the support member may receive a compliant material such as urethane to smoothen the outer surface of the support member. In another embodiment, the hollow interior of the transducer assembly may be filled with a compliant material, such as urethane, which may be provided with air chambers.

Abstract: A piezoelectric sensor comprising at least one pair of flexible sensitive elements of great length whose respective electrodes are connected in parallel. The interconnection is provided by interlacing the sensitive elements so that the two electrodes of each of the flexible sensitive elements are alternately in electric contact with the two electrodes of at least one other sensitive element. The sensor may be formed by winding at least one pair of sensitive elements on a support in two spirals of opposite directions with interlacing. The chosen assembly method provides both good mechanical strength and simplifies the electric connections because of the multiple electric contacts between the electrodes.

Abstract: A hydrophone having a hollow interior with signal electrodes on the interior surface and an electrically conducting coating over the entire outside surface. Signal leads are connected to the inside electrodes and the outside electrically conducting surface is connected to a point of ground potential to form an effective electromagnetic interference shield.

Abstract: In a tubular pressure transducer element, the axial stress imparted to the element is reduced relative to the radial stress by inserting a rigid core inside the tubular element. The reduction in stress is proportional to the ratio between the area of the full diameter of the tubular element and the area of the annulus represented by the wall thickness of the tubular element.

Abstract: An underwater acoustical projector consisting of a spaced apart pair of polygonal shaped end plates, a ceramic driver of smaller cross-sectional size than each end plate, positioned between the end plates, and a set of staves secured from one end plate to the other, each stave being bent concavely inwardly towards the driver and being separated from each other by a gap.

Abstract: An acoustic element assembly used in underwater receivers and projectors comprises two piezoelectric elements bonded to opposite sides of a hybrid circuit substrate (16). The hybrid circuit substrate (16) includes radial slots (32, 34, and 36) which have been cut therethrough. The radial slots (32, 34, and 36) permit a center section (31) to move bidirectionally. Integral micro-electronic circuitry which makes up the receiver or projector is fabricated in the center section (31) on both sides of an alumina ceramic disk (30) using thick and thin film technologies. Piezoelectric cylinders (12 and 14) or piezoelectric hemispheres (22 and 24) are bonded to opposite sides of disk (30) with both conductive and non-conductive bonding materials. The microelectronic circuitry is electrically connected to said cylinders or hemispheres (12, 14, 22, and 24) by conductive lines (44). The acoustic element assembly may be formed by automated techniques and does not require any internal wiring.

Abstract: A piezoelectrically-driven, resonant-pipe projector has formed therein vents to broaden the response of certain cavities resonances and to increase the response between these resonances. The projector exhibits a relatively high electroacoustical efficiency, is capable of medium to high power output over the operating band, and is not depth dependent or depth limited.

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: 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: An accelerometer for underwater acoustic sensors includes a pair of cylindrical piezoelectric crystals configured in a cantilever mode and having attached thereto an electrode segmented into four equal quadrants. In response to translational motion perpendicular to the axes of the piezoelectric crystals, orthogonal voltage signals are generated, from which the crossed dipole directivity patterns can be obtained. The symmetric use of two such piezoelectric crystals enables spurious responses, to rotational motion about an axis perpendicular to the central axis of a cylindrical container for the crystals, to be avoided.

Abstract: A transducer is comprised of a piezoelectric ceramic cylindrical vibrator vibrating radially, and a sheet provided on an outer peripheral surface of the cylindrical vibrator and including a fiber reinforced composite material with fibers oriented only in the direction of central axis of the cylindrical vibrator. Non-piezoelectric cylinder consisting of Al alloy or Mg alloy may be useable instead of the sheet. Another type of transducer includes a cylindrical piezo-transducer vibrating radially, a cylindrical sound radiator with the central axis coincident with the cylindrical piezo-transducer, and a bending coupler provided at a predetermined interval on end surfaces of the two cylinders and coupling the cylindrical piezo-transducer and the cylindrical sound radiator.

Abstract: A tubular acoustic projector for underwater use consists of a ceramic, piezo-electric transducer (21A, 21B) contained in a coaxial, electrically-conductive cylindrical housing (10) whose side wall (11) is thin enough to vibrate with the transducers (21A, 21B). The side wall (11) maintains the transducer under a radial compressive pre-load so as to avoid ceramic failure due to tensile stress. The side wall is sufficiently thermally conductive to dissipate the heat generated in the transducer, in use, to prevent failure of the transducer under the effects of heat. Electrical isolation of the inner and outer surfaces of the transducer is achieved by filling the housing with an insulating liquid.

Abstract: A support for an elongated piezoelectric pressure sensor, which is general cylindrical in shape is mounted on a hollow support member that has a thickness and strength selected to meet desired conditions. The elongated piezoelectric pressure sensor is wound in a helical depression on the exterior of the support member, and the support member in turn is filled with a potting material having a bulk modulus of elasticity selected to provide a sufficient flexibility so that the elongated piezoelectric sensing element generates signals that have a desired sign characteristic and improved acoustic response.

Abstract: Permeation of sea water through the protective rubber housing to the conductive portions of the exterior surface of the ceramic or other pressure-sensitive element results in the development of a low insulation resistance which leads to failure of the unit. The operational life of the unit is extended through the application of an acoustically transparent water impervious layer, interposed and bonded between the exterior surface of the ceramic or other pressure-sensitive element and the interior surface of the rubber housing.

Abstract: A sonobuoy has several components slidably mounted in an elongated tube. The components are longitudinally stacked one above the other at the lower end of the tube when the sonobuoy is in a pre-deployed state and are caused to slide longitudinally upwardly in the tube during sonobuoy deployment to provide a predetermined longitudinal spacing between the components when the sonobuoy is deployed. The components typically include an electronics canister, acoustic wave phase controls and one or more active electroacoustic transducers. The components are attached to a plurality of flexible support cables. The cables are attached at their respective upper ends to the bottom of the canister and are attached at their respective lower ends to the bottom of the tube. The cables are collapsed during the pre-deployed state and tautly extended during the deployed state. Axial guide strips are affixed to the inner surface of the tube.

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: Non-active columnar members are disposed on both sides of an active columnar member consisting of a piezoelectric ceramic material or a magnetically strainable material. Levers are connected to the active and non-active columnar members via first and second hinges. Convex shells are connected to the levers via third hinges. The displacement of the active columnar member is enlarged via the lever action, thereby enabling a miniaturized ultrasonic wave transmitter having high power capability.

Abstract: An electroacoustic transducer ring has an inner vibratile surface defining a ring cavity with a plurality of arcuately spaced electrodes affixed thereto. Planar partitions are placed in the ring cavity. The partition edges are parallel to the ring axis and are attached by a resilient strip to the ring inner surface in the arcuate spacing between the electrodes. The partitions have substantially continuous radial surfaces and when the partitions are substantially coextensive in the axial direciton with the ring axis optimal chordal and diametral isolation between the electrodes is provided.

Abstract: Underwater piezoelectric arrangement in which it comprises two piezoelectric layers made of piezoelectric ceramic-polymer composites, one of the layers has larger hydrophone constant than that of the other layer, and by noise cancelling based on the specific construction of the piezoelectric layers only charges or voltages generated by acoustic waves which act on each layer can be selectively detected. The piezoelectric arrangement may be utilized to provide a piezoelectric cable for use in a submarine earthquake searching or fish finding hydrophone, or an acoustic measuring element under water.

Abstract: A sonobuoy has several components slidably mounted in an elongated tube. The components are longitudinally stacked one above the other at the lower end of the tube when the sonobuoy is in a pre-deployed state and are caused to slide longitudinally upwardly in the tube during sonobuoy deployment to provide a predetermined longitudinal spacing between the components when the sonobuoy is deployed. The components typically include an electronics canister, acoustic wave phase controls and one or more active electroacoustic transducers. The components are attached to a plurality of flexible support cables. The cables are attached at their respective upper ends to the bottom of the canister and are attached at their lower ends to the bottom of the tube. The cables are collapsed during the pre-deployed state and tautly extended during the deployed state. Axial guide strips are affixed to the inner surface of the tube.

Abstract: An acoustic transmitter is employed in a borehole logging tool for generating low frequency acoustic energy waves. A tube of piezoelectric material is sealed at both ends and filled with liquid. A pliable boot surrounds such piezoelectric tube. At least one passageway communicates the inside of the piezoelectric tube with the inner surface of the boot. Differing electrical polarities are applied to the inner and outer surfaces of the piezoelectric tube. These electrical polarities are modulated to excite the piezoelectric tube to resonate at a frequency controlled by the inertia of the liquid in the passageway and the mass of the liquid inside the piezoelectric tube.

Abstract: A cylindrical transducer for use as a low frequency hydrophone and having inner and outer electrodes at least one of which is deposited in a certain predetermined pattern having smooth continuous lines whereby the electrode coverage varies as a function of transducer axial length.

Abstract: A stacked phased array type of transducer has a single electroacoustic transducer element supported intermediately of an elongated tube having a plurality of ports and an end wall at each end thereof for transmitting and receiving acoustic waves broadside the longitudinal axis of the array tube. The element has a first vibratile surface in direct acoustical communication with the external transmission medium and a second vibratile surface in direct acoustical communication with the tube internal transmission medium. The tube is provided with at least one annular port spaced longitudinally from each end of the element for providing acoustic coupling between the internal and external transmission mediums with the tube interior providing acoustic transmission paths internally of the tube communicating between the second vibratile surface and the external transmission medium at each one of the ports.

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: This invention is a transducer support system that couples the weight of the active portion of a transducer to the transducer's flanges without coupling the dynamic motion of the active portion of the transducer to the transducer's flanges. The foregoing invention may be used in a flextensional transducer to produce a transducer with increased acoustic output and lower frequency.

Abstract: A multimode hydrophone of small diameter and low weight providing dipole ectivity patterns over a decade range of low frequencies by utilizing a pair of orthogonal dipole signals and a nondirectional reference signal to eliminate directional ambiguity. Each multimode hydrophone is a thin wall tube divided electrically into quadrants which permits differencing or opposing halves to produce signals with dipole directivity patterns and the formation of a nondirectional reference signal by summing all four quadrants. The hydrophone tube comprises inert and piezoelectric materials, selected and combined so as to shift the resonant frequency of the tube lower while keeping the over-all tube diameter as small as possible.

Abstract: This invention is a small light weight underwater transducer that operates at low frequencies. The foregoing is accomplished by embedding piezoelectric material in the wall of an oval shell between the shell's nodal points. When an alternating voltage is applied to the piezoelectric material, the piezoelectric material expands and contracts causing large circumferential strains in the shell of the transducer. The aforementioned strains cause the shell to vibrate and energy to be radiated into the water. This invention may also be used as a receiving type of transducer.

Abstract: This invention is a device that permits a flextensional transducer to function after the flextensional transducer experiences a pressure equal to or greater than the pressure found at the survival depth of prior art flextensional transducers. The foregoing is achieved by not bonding at least one end of the transducer's piezoelectric stack to the transducer's shell and having the other end or ends of the piezoelectric stack held in the vicinity of the transducer's shell by a pair of guide rails, etc. This permits the transducer's shell to move away from at least one end of the piezoelectric stack at pressures equal to or greater than the pressure at which the stack would experience tensile stresses in a conventional flextensional design. Thus, the piezoelectric stack will not fracture since it receives no tensile stress.

Abstract: An electro-mechanical transducer is disclosed in which a piston-like radiating element is driven by fluid pumped from the interior of a flextensional transducer such that the motion of the flextensional transducer shell is transmitted to the radiating element.

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: An acoustical logging tool having a plurality of long, extendable, resilient arms, and means for remotely extending free ends of the arms into close proximity to the wall of a borehole. A cylindrical transducer is mounted on the free end of each arm, with some of the transducers being used as transmitters and the remainder as receivers. The signals from the receivers are separately recorded to provide a side-by-side comparison of the signals. The proper spacing of the transmitters and receivers will produce a complete circumferential acoustic log of the borehole that can be used to detect the presence of vertical fractures.

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.

Abstract: A seismic source for downhole use is disclosed which is formed by an outer tubular member having weighted ends which carries within a coaxially mounted tubularly shaped piezoelectric element. The piezoelectric element is cyclically driven to produce a standing wave having a frequency in the range of 0.25 to 5 kHz and a narrow bandwidth in the range of 5-50 Hz.