Abstract: An improved method for fabrication of a multiple-element piezoelectric transducer and the transducer produced thereby. A green precursor tape is produced by doctor-blade tape-casting of a slurry containing lead zirconate-titanate (PZT) powder. After drying, individual strips of the tape are stacked between flat plates of previously sintered PZT, and sintered to form PZT strips; Pb from the previously sintered PZT plates makes up any Pb lost from the surfaces of the tape strips during sintering. The PZT strips are stacked interposed by layers of a thermoplastic polymer, and heated to a temperature above the melting point of the polymer, forming a laminate block. This block is then sliced perpendicular to the plane of the layers, forming slabs of alternate PZT and polymer layers; the slabs are then sliced perpendicular to the first slicing planes, forming strips of alternating PZT and polymer material. Electrodes are then added to complete the transducer assembly.

Abstract: A pressure compensated hydrophone assembly consists of a hollow mandrel that has an outer surface. The central portion of the outer surface of the mandrel defines a concavity. A flexible, resilient piezoelectric film is wrapped several times around the mandrel. The volume between the inner wrap of the film and the concavity on the outer surface of the mandrel serves as a pressure compensation chamber. The hydrophone is responsive to varying hydrodynamic pressure fields but is substantially inert to acceleration forces, localized impacts and variations in hydrostatic pressure.

Abstract: The invention relates to a piezoelectric element comprising a piezoelectric material 1, in the form of a polymer network, between at least two electrodes 2, 3. The piezoelectric material is formed from a starting material comprising a liquid crystalline monomeric material and a chiral compound. The starting material is brought to a temperature at which a smectic phase is formed, and an electric field is applied to obtain a dipolar orientation in the starting material, after which the polymer network is formed by means of photopolymerisation. The piezoelectric element thus manufactured can suitably be used for various electromechanical applications, as a sensor material, for pyroelectric applications and, in particular, also for optical applications.

Abstract: A piezoelectric film strip is wrapped a plurality of times around a flexible inert mandrel that has standoff collars on each end. The film-wrapped mandrel is hermetically sealed inside a hollow rigid inert cylinder. Electrodes provide electrical communication with the film strip which forms the active element of the transducer. Variations in hydrodynamic pressure flex the film strip in tension to generate a voltage.

Abstract: A ballistic fuse, which converts mechanical energy derived from the initial firing to stored electrical energy used to energize a later detonation, having piezoelectric polymer film strip with oppositely polarized layers on opposite surfaces, is pre-folded end to end before pleating and stacking in order to place both halves of a surface layer of one polarity into mutually contacting relationship, thereby reducing the risk of short circuits, and furthermore to double the bend radius required for pleating, thereby decreasing the risk of hinge failure due to bending stress at the pleated folds, and the continuous pattern of circles joined side by side in each layer is printed with conductive silver ink on the polymer film to eliminate the necessity of joining surfaces of like polarity with individual leads.

Abstract: An acoustic device, such as a membrane hydrophone, includes a support structure and an outer membrane that suspends a transducer membrane within the interior of the support structure. The transducer membrane is selected for its acoustic and piezoelectric properties and is preferably a polymer such as P(VDF-TrFE). The outer suspension membrane is selected primarily for its mechanical properties. Portions of the suspension membrane may be removed in order to reduce mechanical drag encountered during movement of the device in a liquid. The transducer membrane includes at least one active area that is poled to provide a piezoelectrically strong region. Electrical charge generated at the active area is amplified at a preamp for transmission to remote equipment.

Abstract: A device for determining which zone on a target has been struck by an object. The device is made of a frame, and a flexible support means which is mounted on the frame, and is disposed in the path of a moving object. A transducer made of piezoelectric film, coated with a conductive coating on each of its surfaces to form electrodes, is mounted on the flexible surface. Attached to the electrodes of the transducer are leads which transmit electrical pulses to a signal processing unit. An object striking the target produces an electrical pulse which is translated by the signal processing unit and which determines the zone on the target which was struck by the object.

Abstract: A piezoelectric composite which can be used as a transducer is constructed of parallel piezoelectric ceramic rods set in a passive polymer matrix which has a negative Poisson ratio whereby the electromechanical coupling of the transducer is greatly increased.

Abstract: A wideband ultrasonic transducer comprises at least two stretched piezoelectric polymer films rolled together in a lengthwise direction so as to form a scroll having an axis parallel to a stretch direction of the polymer films. Each of the polymer films has a different width W in a longitudinal direction of the scroll, where the widths W are related to respective acoustic wavelengths .lambda. of the polymer films. A resonant frequency of each polymer film is selected by varying the widths W of each polymer film and the resonant frequencies of the polymer films are preferably selected so as to occupy a desired contiguous frequency band. An electric field is applied to each of the polymer films in parallel so as to induce expansion or shrinkage of the polymer films in their stretched directions, thereby causing resonance at their respective resonant frequencies.

Abstract: A pressure pulse source for generating acoustic pressure pulses in an acoustic propagation medium has a foil arrangement formed by a number of electrically contacted piezoelectric foils stacked directly on top of one another with no interstices between the foils, and employs a drive system for driving the individual foils in succession according to the traveling wave principle.

Abstract: The invention relates to a method for manufacturing an acoustic sensor, and also to the sensor. The sensor comprises a piezoelectric sheet (12) mounted on a support (14) and electrically connected to electrodes (16,18) connected by electrical conductors (20,22) to a measurement device, characterized in that the assembly constituted by the sheet (12) and its support (14) is coated with a one-piece polymerizable coating layer (24) which is preferably electrically insulating, such that the portion (24a) of the coating layer (24) overlying the sheet (12) constitutes a protective layer which is rendered non-detachable or essentially non-detachable from the piezoelectric sheet (12). The method for manufacturing this sensor is extremely simple and inexpensive, and the protective layer is non-detachable.

Abstract: An actuator element comprises an ion exchange membrane and a pair of electrodes attached to opposite surfaces of the ion exchange membrane; the ion exchange membrane in a water-containing state being caused to bend and/or deform by application of an electric potential difference thereacross.

Abstract: A high unidirectivity piezoelectric element whose d.sub.31, d.sub.33 or d.sub.h is substantially zero. The element may be in the form of a sheet or a cable and includes a pair of electrodes, and a piezoelectric layer interposed between the pair of electrodes and containing two, first and second inorganic piezoelectric materials which have different coercive forces from each other and which are polarized in opposite directions. The element may be obtained by first applying a direct current voltage to a layer containing the first and second piezoelectric materials to polarize the both piezoelectric materials in one direction, and then applying a reverse direct current voltage thereto so that one of the piezoelectric materials having a smaller coercive force is selectively polarized in the other direction.

Abstract: The provided invention is a novel electrostrictive driving device which comprises a sonic wave projector element having alternating electrodes and polymer material film layers. The device provides when subjected to a high bias voltage and a superimposed A.C. voltage, a high Angstroms/Volt response. Also, provided is a process for projecting sonic waves using the electrostrictive driving device of this invention.

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 piezoelectric electro-acoustic device for converting an electric signal into an acoustic vibration and/or for converting acoustic vibrations into an electric signal is disclosed. The device employs at least two opposing concave membranes having a single axis of elongation tangent to the curvature thereof. The membranes face each other and are connected to electrodes. Upon changes in electric current provided to the membranes, the membranes will vibrate towards one another to thereby displace air located between the surfaces thereof. This dipole horn structure provides a high conversion efficiency as well as a true 360.degree. acoustic response.

Abstract: A device to eliminate ice formed on the surface of a wall, notably on the surface of an optical or radio-electric window, comprises a piezoelectric material having a vibrating active surface that mechanically cooperates with the wall to be de-iced, and means for the polarization of this piezoelectric material, comprising an AC voltage source and conducting or semiconducting electrodes placed in contact with this material according to a geometry capable of generating, within this material, an acoustic wave that has a direction of vibration which is oriented longitudinally and/or transversally to said surface to be de-iced, the amplitude of this vibration being sufficient to respectively detach and/or break the deposit of ice formed on said surface. The piezoelectric material is preferably a ferroelectric polymer such as a polymer of the group comprising PVF.sub.2, PVF.sub.2 -TrFE, PVDCN-VAc, PVF.sub.2 -TFE and the mixture of these polymers with one another and/or with PMMA or PEMA.

Abstract: A flexible ultrasonic contact transducer comprises an unpoled polymeric film layer and a poled piezo film layer. Electrode shielding layers are disposed on outer surfaces of the unpoled polymeric film layer and poled piezo film layer. A quarter wave reflector is disposed between inner surfaces of the two layers. An ultrasonic contact transducer array comprises a common poled piezo film layer and a common backing/insulating layer. A plurality of quarter wave reflector elements are disposed between inner surfaces of the poled piezo film layer and backing/insulating layer. Shielding electrodes are disposed on the outer surfaces of the two layers. A polymeric shielding layer is preferably disposed around the quarter wave reflectors. Lead means provide an electrical path from the quarter wave reflectors to a common edge of the array.

Abstract: An ultrasonic sensing array having ultrasonic transducer elements formed on a micromachined single-crystal semiconductor wafer provided with a deep recess under each transducer. Etch-altering dopants are diffused into the water to form rimmed support structures for dielectric stress-balanced elements. Composite dielectric layers are grown on both surfaces of the wafer. One composite layer serves as a diaphragm underlying the transducer elements. The other composite layer serves as a mask for etching away the substrate under each transducer element to form the deep recess while leaving the support structures and diaphragm layer. The resulting hollow or recess under each transducer element reduces the parasitic capacitance between the transducer and support substrate. The transducer elements are made by forming conductive bottom plates on the dielectric diaphragm layer, adding a piezoelectric polymer layer and thereafter forming the conductive top plates.

Abstract: An ultrasound sensor has a piezoelectric foil polarized in at least in one region, a signal electrode arranged at one side of the piezoelectric foil, and comprises a shell electrode arranged at the other side of the piezoelectric foil. The piezoelectric foil, the signal electrode and the shell electrode are component parts of a multilayer structure wherein the signal electrode and the shell electrode are separated from the piezoelectric foil by a dielectric coupling layer, and the signal electrode and the polarized region of the piezoelectric foil overlap in a region forming a pressure-sensitive sensor surface.

Abstract: A method of forming a laminated piezoelectric structure is disclosed wherein a plurality of polarized piezoelectric films of vinylidene fluoride and trifluoroethylene are solvent welded together. The solvent welding solution comprises a copolymer of vinylidene fluoride and trifluoroethylene and a suitable solvent. The transducers produced from such a laminated structure are also disclosed.

Abstract: An acoustic transducer which can be made small in size, i.e., in width, length and thickness, so as to fit into a credit card size package. The transducer comprises a flat frame having an opening therethrough. A pair of diaphragms of a piezoelectric plastic material extend across the opening in the frame along opposite sides of the frame. The diaphragms are stretched in at least one direction and are bonded to the frame under tension in the direction of the stretch. The diaphragms are bonded together at a position within the opening in the frame. The diaphragms are coated in both surfaces with conductive metal films. The inner metal films on the diaphragms which are opposed to each other are electrically connected together and the outer metal films are electrically connected together.

Abstract: A material sensor employs deflectable means and piezoelectric film means for providing signals indicative of a material condition.

Abstract: The invention relates to a piezoelectric acceleration sensor and to a piezoelectric acceleration device which use a film piezoelectric element.Speicfically, the piezoelectric acceleration sensor and the piezoelectric acceleration sensor device generate relatively large outputs when acceleration occurs along the sensing axis, but produce relatively small outputs from acceleration perpendicular to the sensing axis. In addition, the sensor and the sensor device are relatively unaffected by temperature fluctuations and are highly impact-resistant.

Abstract: An acoustic field transducer (10) comprises an elastic membrane (15A) made of piezo-electric material and peripherally held in stretched condition with static strain. A major surface area of the membrane (15A) is free to move in response to acoustic field variations which are coupled to the membrane (15A). Electrical conductors (17) are connected to the membrane (15A) for collecting signals piezo-electrically generated by the membrane due to strain variations and which are a measure of the acoustic field variations. The acoustic field variations are coupled to the membrane (15A) in a variety of different arrangements.

Abstract: A self-orienting vertically sensitive accelerometer is disclosed for measuring a vertical component of acceleration independently of the orientation of the accelerometer. The accelerometer of the present invention includes a spherical plastic shell having a plurality of perforations disposed therein and a thin film of metallic coated piezoelectric polymer bonded to the exterior thereof, forming a small diaphragm at each perforation. In response to acceleration a dynamic pressure is developed within a fluid mass partially filling the spherical plastic shell which creates a strain and resultant charge in each small diaphragm of piezoelectric polymer. The vast difference in density between the fluid mass and the air in the remaining volume of the spherical plastic shell permits the charge developed in each small diaphragm under fluid pressure to be attributed solely to the vertical component of acceleration applied to the fluid mass.

Abstract: A pressure sensitive pad assembly for a brake pedal having in one embodiment a pair of plastic films with metallized surfaces spaced apart by apertured spaces and embedded in an elastomeric pad to be placed on a brake pedal. Application of a brake actuating force on the pad causes the elastomer to deform closing contact between the metallized surfaces for actuating a brake light. In another embodiment a pressure sensitive transducer pad assembly has embedded in elastomeric material, a plurality of piezoelectric strips which are deformed, upon application of a brake actuating force to the pad, for providing an electrical signal indicative of the magnitude of the brake actuating force. In another embodiment an elastomeric pad spans a shallow recess in a support with piezoelectric material provided on the spanning surface and deformation of the pad into the recess deforms the piezoelectric material to provide a brake actuating force signal.

Abstract: Electroacoustic novelties are disclosed having a piezoelectric polymer film which functions as a speaker or microphone. The novelties include flags, banners, posters or articles of headwear. The piezoelectric polymer film may be attached to a portion of the flexible substrate forming the novelty, or it may be used as an integral part of the novelty structure. An audio output or recording device is electrically coupled to the piezoelectric polymer film. Both the piezoelectric polymer film and the electrodes may be transparent so that the adjoining portion of the novelty is visible.

Abstract: A structure for a piezo film impact detector eliminates or minimizes false outputs due to pyroelectric effects. The detector structure has particular application to outdoor and underground use.

Abstract: Disclosed is a vinylidene cyanide copolymer obtained by copolymerization of vinylidene cyanide and two kind of vinyl compounds.By formation of a ternary copolymer, a monomer difficultly copolymerizabke with vinylidene cyanide can be incorporated into the polymer, and high piezoelectric performance can be obtained when polarized.

Abstract: An infrared detector array or other electrical transducer device comprising an electrically-active film (10) of polymer material is manufactured with a pattern of electrodes (11) embedded at one face of the film (10). The electrodes (11) are formed on a support (4,5) as a photolithographically defined pattern of deposited material. These electrodes (11) are then transferred to the film (10) by depositing the film material on the support (4,5) and over the electrodes (11) and removing the support (4,5) at least at the area of the electrodes (11). The polymer material of the film (10) bonds well to the electrodes (11). In this manner, fine-geometry patterns of thin electrodes (11) can be formed embedded in the face of the film (10) and having reproduceable electrode characteristics for charge detection at the film faces in piezoelectric pyroelectric and ferroelectric devices.

Abstract: A piezo film switch comprises a cantilever with a pair of layers, including a piezo film layer and a flexible, backing layer laminated thereto. The piezo film layer produces a positive or negative output pulse, depending upon a direction of deflection of the cantilever. Interface circuitry coupled to the piezo film layer is powered by the output pulses and provides "pseudo contact closures" which emulate the operation of a mechanical switch.

Abstract: Disclosed is an ultrasonic probe using a compound piezoelectric material made of piezoelectric ceramic and organic polymer. On one principal plane of the compound piezoelectric material, electrodes and electric terminals conducting to these electrodes are formed, and these electrodes and electric terminals are divided into a plurality. On the other principal plane of the compound piezoelectric material, a common electrode is provided, and an acoustic matching layer is mounted on it either intact or divided in correspondence to the divided electrodes. By using part of the compound piezoelectric material as the electric terminal take-out portion, the mechanical strength of the electric terminal take-out portion can be improved, which is particularly preferable for the ultrasonic probe driven at high frequency.

Abstract: A piezoelectric transducer of piezoelectric plastic material comprises a body and activated transducer film formed integrally. Electrodes are formed on opposite sides of the film, and a backing material supports the film on one side. The transducer may be formed by molding, applying the electrodes and activating the film by means of a corona discharge.

Abstract: A sensor tip (10) for use in a robotic hand has a three-dimensional compliant elastomeric body (12) with an outer boundary (22) having a circular base (24) and a convex surface (26) extending therefrom. Four strain transducers (14, 16, 18, and 20) produce electrical signals indicative of the strain at various positions near the boundary of the elastomeric body (12) resulting from forces exerted upon the sensor tip (10) by an object which the robotic hand is manipulating. The transducers (14, 16, 18, and 20) are positioned about the convex surface (26) so as to produce signals that may be decoupled to determine the normal and tangential forces and the applied torque. A buffer amplifier circuit (34), one for each of the transducers (14, 16, 18, and 20), receives the signals and provides quasi-steady state force information. The circuit (34) connects the respective transducer (40) in a feedback loop around an amplifier (36) and has desirable attributes for static charge buffering.

Abstract: In an electric device having a package included an electric circuit element therein, a cooling fan is fixed on the package directly. The fan is formed of piezoelectric elements and a flexible cooling fin. The fan generates the cooling air flow due to vibration of the piezoelectric elements.

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 900% improvement in force step response rise time and a 300% reduction in overshoot are possible through the use of the PVDF sensor.

Abstract: A piezoelectric transducer array comprises a plurality of piezoelectric transducer means arranged in an array. A common electrode is provided among at least a plurality of the piezoelectric transducer means. A plurality of discrete signal electrodes is operatively associated with each transducer means. The number of signal electrodes for each transducer means is the same. The surface areas of the signal electrodes for each transducer means are adapted and arranged for generating a signal unique to each transducer means. Corresponding ones of the signal electrodes of each plurality of signal electrodes are connected together with a common conductor to form a single electrical terminal. The total number of resulting electrical terminals is the same as the number of signal electrodes for each transducer means.

Abstract: A sensor comprising a deformable medium, such as rubber, an ultrasonic transducer for transmitting a signal through the medium to a face of the medium and for sensing an echo of the signal returned from the face through the material to the transducer and circuit means for determining the time differential between transmission of the signal and return of the echo and for converting the time signal into a distance measurement.

Abstract: A sensor, having a sandwich configuration, is able to sense a transduce out parameter in situ without significantly affecting the parameter. The sensor comprises an inner sheet of a polymer having a transducer property. A conductive layer is deposited on parts of at least one of the two surfaces of the inner sheet. A pair of outer sheets of plastic are attached to each side of the inner sheet. Two layers of conductive material may be deposited on the outer, unattached, surfaces of the outer sheets, one layer on each surface.

Abstract: A composite sheet transducer for producing voltage in response to stimuli d having a polymeric sheet sandwiched between a plurality of thin film conductive blocks arranged in non-conductively isolated block patterns of opposed electrode assemblies to establish a network of closed circuit segments of sensors. Electric shorting between opposed overlapping blocks is thereby limited to circuit segment areas of the composite sheet to avoid interference with voltage production in other areas of the composite sheet.

Abstract: An arrangement for finding the direction of a sound in a medium has a thin shell structure having a circular symmetry. The structure can flex in response to incident sound energy from the medium to perturb the form of the structure. A membrane of a piezo-electric material with an anisotropic piezo-electric response to distortion is arranged to be distorted by the perturbation of the thin shell structure. The response of the membrane to this perturbation permits the direction of the incident sound to be indicated. The membrane can be of polyvinylidene difluoride with anisotropic properties. The membrane may be formed into a "dome" for example by fluid pressure inside a hemispherical shell closed by the membrane.

Abstract: Piezoelectric materials characterized by consisting essentially of crosslinked polyphosphazenes obtained by bringing polyphosphazenes which have repeating structural units represented by the general formula [I]--NP(X).sub.a (Y).sub.b -- [I](all the symbols are as defined in the appended claims) into oriented state in an electric field provided by applying high voltage on them and then crosslinking them under such conditions.Piezoelectric materials thus obtained display an excellent piezoelectric effect and, in addition, rubber elasticity.

Abstract: A hydrophone mounted on the hull of a ship comprises an electromechanical ansducer made of void-containing ceramic material having a high piezoelectric sensitivity to water-borne acoustic sound signals, a transducer made of solid ceramic material having a low piezoelectric sensitivity to hydrostatic acoustic signals, both transducers having similar piezoelectric sensitivity to shipboard noise transmitted via the ship's hull and transducer mounting; and means for sensing and manipulating voltage signals generated in response to water-borne acoustic signals and mount-transmitted shipboard noise such that the mount transmitted noise signals are largely cancelled out and a relatively noise-free signal representing hydrostatically transmitted sound is obtained.

Abstract: A piezo-electric acceleration sensor, including: a piezo-electric polymer membrane element having an element through-hole; a diaphragm having a diaphragm through-hole and attached to the piezo-electric membrane element so that the diaphragm hole is concentric to the element through-hole to form a laminate with a laminate through-hole; and a fixing mechanism, having a sensing hole, for fixing the laminate in a stretched manner, and wherein: the laminate through-hole has about 2.25 to about 80% of the area of the sensing hole; and the diaphragm and the piezo-electric element meet the equation:(Eb.times.Tb.sup.3)/(Ep.times.Tp.sub.3).gtoreq.about 5wherein Eb, Tb, Ep and Tp are Young's modulus thickness of the diaphragm, Young's modulus, and thickness of the piezo-electric element, respectively, whereby acceleration, applied to the diaphragm, is detected based on a quantity of electricity generated due to strains in a piezo-electric element.

Abstract: Apparatus for determining inter-pen offsets in a multiple pen ink jet printer including a piezoelectric ink drop detector having a piezoelectric detector film having one or more openings formed therein. A carriage position sensor indicates the position of the carriage at the time a first ink drop is detected from each of the ink jet pens as the pens are scanned across an opening, whereby the sensed positions for the respective pens provides information indicative of inter-pen offset in the scan direction. For determination of inter-pen offset in the media scan direction, the piezoelectric film includes a plurality of openings, whereby the detect/no detect patterns for each of the pens provides information indicative of the inter-pen offsets.

Abstract: A tubular piezo-electric sensor has at least one sensitive element disposed against an outer surface of a tubular support. A substance whose acoustic impedance is very different from that of the material forming the tubular support is disposed therein and a remaining volume of the tubular support is filled with liquid. Glass fiber cords or open cell foams, for example, are used as the substance, and the liquid may, for example, be that which fills a seismic streamer and, in this case, the tubular support is left open. The tubular support may also be closed at both ends by sealed caps and included in a protective sheath. The dimensions of the tubular support and the material from which it is made are chosen so as to optimize the sensitivity of the piezo-electric sensor.

Abstract: An ultrasound sensor is used for measuring the sound pressure amplitude in the focal range of focused ultrasound shock waves. The sensor contains a polymer foil which is piezoelectrically activated in one region and is coupled to electrodes which are physically separated from the region. The polymer foil is arranged in a hollow plastic cylinder with its flat surface sides parallel to the central longitudinal axis of the hollow cylinder. By this measure, interfering diffraction effects are reduced and miniaturization of the ultrasound sensor is achieved.

Abstract: An amusement device is disclosed which contains a signal generator attached to a flexible member. When the flexible member is repeatedly waved, an oscillatory electrical signal is produced by the signal generator and supplied to a sound generator which produces sound which synchronously varies with the repeated flexure of the member caused by the waving action. The sound generator produces a first tone with respect to the oscillatory electrical signal and a second tone when the frequency of the oscillatory electrical signal exceeds a predetermined value.

Abstract: A hail sensor is disclosed which contains a piezoelectric transducer positioned to produce an output signal when it is vibrated by a hailstone. In one embodiment, the transducer is mounted on a perforated member which is exposed to falling precipitation. In an alternative embodiment, the hailstone impacts a rebound surface and is deflected toward the transducer where an electrical output is produced.