Abstract: A piezoelectric fan comprises a blade (110, 210, 310, 410, 510, 610), a piezoelectric actuator patch (120, 220, 320, 420, 520 ,620, 811) adjacent to the blade, and a piezoelectric sensor patch (130, 230, 330, 430, 530, 630, 812) adjacent to one of the piezoelectric actuator patch and the blade. The piezoelectric sensor patch measures a voltage proportional to a deflection of the piezoelectric actuator patch and a deflection of a tip of the blade and uses that voltage to generate an input signal to an active feedback controller (840) that in turn ensures that the oscillation amplitude of the blade satisfies certain cooling specifications.

Abstract: A piezoelectric package comprises an upper and lower piezoelectric plates, each having opposing electrodes. The piezoelectric package further comprises an electrically insulative structure encapsulating the piezoelectric plates. The piezoelectric package further comprises first and second external connectors mounted to the insulative structure. The connectors respectively have connector terminals that are electrically coupled to the electrodes in different orders, and have geometric arrangements that are identical, such that a single interface device can be selectively mated to either of the connectors. The piezoelectric package may be incorporated into a system that comprises electronic circuitry configured for operating the piezoelectric package, and a single interface device electrically coupled between the electronic circuitry and either of the external connectors of the piezoelectric package to selectively configure the package between a unimorph and a bimorph.

Abstract: An ultrasound system for providing megasonics and ultrasonics to a liquid at different frequencies and/or sweeping frequencies with associated generators, transducers, operations between resonance and anti-resonance, non-resistive output with phase shift, multiple/sweep/single frequency modes, individually controlled sections, gate drive power control, variable inductive compensation for temperature changes, parallel inductor matching, stacked ceramics and non-volatile memory storage of fault, error and failure history.

Abstract: An actuator driving apparatus comprises the following. A start signal generator generates a start signal having a frequency substantially equal to the resonance frequency of the movable portion of an actuator. A rock detector detects rock of the movable portion. A drive timing signal generator generates a drive timing signal based on the output of the rock detector. A switch is connected to the start signal generator and drive timing signal generator for selectively transmitting their outputs to a section arranged in a subsequent stage. A drive signal generator generates a drive signal based on the output of the switch, and supplies it to the actuator. A superposition preventing section prevents a frequency component of a frequency substantially equal to the resonance frequency from being superposed upon the output of the rock detector. The apparatus performs driving according to the rocking state of the movable portion, by switching the switch.

Abstract: A piezoelectric detector circuit has at least one input line, a piezoelectric transducer in the input line, an amplifier receiving signals on the input line and generating an output, and one or two feedback elements through which the output is sent back to the input line. The circuit may be a discrete time sampled operational amplifier (DTOA) based transconductance or “voltage output mode” circuit. In one embodiment, protection elements are associated with amplifier input lines to establish a reference voltage.

Abstract: A magnetostrictive ultrasonic dental scaler is disclosed. The magnetostrictive device comprises an oscillator adapted to provide electrical energy including a current and a voltage signal, a handpiece having a tool tip which vibrates in response to the electrical energy supplied to the handpiece and a control circuit. The control circuit includes a phase detector adapted to detect phase between current and voltage signals and to generate a phase detection signal as a function of the phase. The control circuit also includes a digital signal processor operatively connected to the phase detector. The digital signal processor adapted to process the phase detection signal through a digital loop filter to generate an error signal.

Abstract: In an energy recovery type surface acoustic wave motor, an increase in energy efficiency at the time of energy recovery and supply is achieved by adjusting phase change.

Abstract: A variance in transmitting/receiving sensitivity between multiple vibrational elements or transducers included in an ultrasonic probe is corrected. An ultrasonic probe in accordance with the present invention has multiple transducers, each of which includes multiple vibrational elements that each transmit or receive ultrasonic waves by converting ultrasonic waves and an electric signal into each other with a bias voltage applied thereto, set in array. The ultrasonic prove includes a transmitting/receiving sensitivity correction means that independently adjusts the bias voltage to be applied to at least two vibrational elements among the multiple vibrational elements so as to correct a variance in transmitting/receiving sensitivity between the at least two vibrational elements.

Abstract: A megasonic processing apparatus and method has one or more piezoelectric transducers operating in thickness mode at fundamental resonant frequencies of at least 300 KHz. A generator powers the transducers with a variable-frequency driving signal that varies or sweeps throughout a predetermined sweep frequency range. The generator repeatedly varies or sweeps the frequency of the driving signal through a sweep frequency range that includes the resonant frequencies of all the transducers.

Abstract: A power supply device generates an output voltage by driving a piezoelectric transformer using a frequency signal. The power supply device includes a comparison unit configured to compare an output voltage and a voltage setting signal that sets the output voltage, and a voltage control oscillation unit configured to generate the frequency signal to drive the piezoelectric transformer based on comparison results of the comparison unit. The voltage control oscillation unit generates the frequency signal within a range between the resonant frequency and a spurious resonant frequency closest to the resonant frequency.

Abstract: An ultrasonic motor that is capable of stable driving by preventing uneven rotation of a driven body and maintaining the drive efficiency is provided. The ultrasonic motor includes a plurality of ultrasonic transducers including alternately stacked first piezoelectric elements and second piezoelectric elements, and a control unit for applying the same two-phase driving AC voltages to the plurality of ultrasonic transducers. The ultrasonic motor simultaneously generates longitudinal vibration and flexural vibration at the ultrasonic transducers to generate substantially elliptic vibration at output ends of the ultrasonic transducers and relatively moves the ultrasonic transducers and a driven body in contact with the ultrasonic transducers.

Abstract: The invention provides an ultrasonic motor including internal electrodes provided in an ultrasonic vibrator and disposed in regions where electrical charges of the same sign are generated in one vibration mode and where electrical charges of opposite sign and substantially the same amount are generated in another vibration mode; and a control unit configured to detect a phase difference between a vibration detection signal detected on the basis of electrical signals from the internal electrodes and any one of driving AC voltages, and to set a driving frequency such that the phase difference becomes a reference phase difference. Each driving AC voltage with the driving frequency set by the control unit is applied to the ultrasonic vibrator.

Abstract: Disclosed is a structural vibration damping device, which comprises a piezoelectric element adapted to be mounted on a structure, a shunt circuit inserted between two electrodes of the piezoelectric element, and an electric circuit for selectively opening and closing the shunt circuit. In this damping device, the electric circuit is operable, when a voltage between the electrodes of the piezoelectric element has a positive or negative extreme value due to a vibration of the structure, to close the shunt circuit so as to allow a current to flow between the electrodes of the piezoelectric element, and, when the current is reduced to zero, to open the shunt circuit so as to preclude the current flow until a voltage between the electrodes of the piezoelectric element subsequently has the extreme value. Further, each of the shunt circuit and the electric circuit is designed to be operated using only a power generated by the piezoelectric element.

Abstract: Liquids are treated by ultrasound in a flow-through reaction vessel with an elongate ultrasonic horn mounted to the vessel with one end of the horn extending into the vessel interior. The liquid flow path inside the vessel is such that the entering liquid strikes the end of the horn at a direction normal to the end, then flows across the surface of the end before leaving the vessel. The end surface of the horn is positioned in close proximity to the entry port to provide a relatively high surface-to-volume ratio in the immediate vicinity of the horn end. In a further improvement, the horn is joined to an ultrasonic transducer through a booster block that provides an acoustic gain to the ultrasonic vibrations, and the booster block is plated with a reflective metal to lessen any loss of ultrasonic energy being transmitted to the horn.

Abstract: The present invention relates to methods for velocity control of transducers that can compensate both for age related changes as well as the more immediate changes that occur during operation. In one aspect of the invention, the non-motional reactive current is measured at two predetermined frequencies, one below (Ilf) and one above the resonance frequency (Ihf). A correction factor is calculated from these measured currents is used to maintain a specified value of end effector velocity or displacement. In another aspect of the invention, methods are provided for the detection of secondary resonances that could be indicative of end effector fault conditions. In another aspect of the invention, velocity control is achieved.

Abstract: A system and method for measuring absolute pressure applied to a piezoelectric element by measuring a transition time of a voltage pulse applied to a piezoelectric element. The transition time (such as the rise time and/or fall time of the voltage pulse) is affected by the capacitance of the piezoelectric element, which in turn is affected by the amount of pressure currently being applied to the piezoelectric element. The system may also provide haptic feedback via the same piezoelectric element.

Abstract: A micro-electro-mechanical transducer (such as a cMUT) is disclosed. The transducer has a substrate, a top plate, and a resilient structure therebetween. The resilient structure has multiple connectors distributed over the device element area to vertically transport the top player with distributed support. The resilient structure may be cantilevers formed using a middle spring layer covering cavities on the substrate. Connectors define a transducing space below the top plate. The resilient structure enables a vertical displacement of the connectors, which transports the top plate in a piston-like motion to change the transducing space and to effectuate energy transformation. No separate cells are necessary for each addressable transducer element. Multiple device elements can be made on the same substrate.

Abstract: In a control system and method for operating an ultrasonic liquid delivery device a first drive signal is delivered according to a first drive signal control schedule to an ultrasonic waveguide assembly to excite the ultrasonic waveguide for a predefined time. At each of a plurality of instances of the first drive signal control schedule a phase angle associated with the current and voltage in the waveguide assembly during ultrasonic vibration thereof is determined. A second drive signal control schedule is determined, including a second ultrasonic drive signal frequency for each of the instances at which the phase angle of the first drive signal was determined. The second drive signal frequency at each of the instances is based at least in part on the phase angle determined at each instance during ultrasonic vibration of the waveguide assembly in accordance with the first drive signal control schedule.

Abstract: The invention disclosed that the multiple frequency ultrasound apparatus using unique transducer will contain many actuations module, a coupled circuit and a transducer. Each actuation module can separately output the signal of the different frequency, the coupled circuit connecting the actuation module for coupling with the signal of the different frequency. The transducer can receive the signal of the multiple frequencies, then for outputting the multiple ultrasound frequency by the way of transferring from the electrical energy to the mechanical energy.

Abstract: A system that facilitates damping of mechanical vibration associated with machinery that is subject to such mechanical vibration. The system comprises machinery with at least one moveable part and a piezoelectric actuator that is selectively applied to the machinery. The piezoelectric actuator receives voltages and is employed to facilitate damping of mechanical vibration associated with the machinery.

Abstract: An actuating device including a load and an integrated electronic control circuit comprising a microcontroller and at least one passive component. The microcontroller performs the dual function of providing a control signal to generate sufficient power to actuate a load and a drive signal to drive the load.

Abstract: Transducers employing electroactive polymer films are disclosed.

Abstract: Provided is a multiplexer for a biometric apparatus. The multiplexer includes a plurality of first conductors coupled to the first ends of piezo ceramic elements in corresponding rows and a plurality of first switches each of which is coupled to a respective one of the first conductors and a plurality of second conductors coupled to the second ends of piezo ceramic elements in corresponding columns. The multiplexer also includes a plurality of second switches each of which is coupled to a respective one of the second conductors. The first conductors are approximately orthogonal to the second conductors, and the first switches are controlled to couple a signal output from an output port of the signal generator to a particular piezo ceramic element of the at least twenty five thousand piezo ceramic elements. The second switches are controlled to couple a signal associated with the particular piezo ceramic element of the at least twenty five thousand piezo ceramic elements to an input port of the processor.

Abstract: A fuel injection device of an internal combustion engine includes a piezoelectric actuator and a valve element that are coupled to one another. The valve element has a pressure stage. An increase in the force acting on the piezoelectric actuator is interpreted as an actual opening of the valve element, and/or a decrease in the force acting on the piezoelectric actuator is interpreted as an actual closing of the valve element, and that these be taken into account at least part of the time in the controlling of the piezoelectric actuator.

Abstract: A piezoelectric transducer drive circuit comprising a variable current source being controlled by a differential operational amplifier, a constant current source and a switch means connected in series with the variable current source between a power supply voltage VDD and the ground potential, and a capacitor having opposite ends connected with the output of the variable current source and one input terminal of the differential operational amplifier, wherein the switch means takes nonconducting state upon stoppage of applying operation of intermittent operation and takes conducting state at the time of applying operation, and an error reference voltage VREF1 takes a first value upon stoppage of intermittent operation and transits gradually to a second value as the operation is started. Overshoot current of a cold cathode ray tube can be deterred when applying operation of intermittent operation is started.

Abstract: A MEMS device comprising a substrate; an anchored end connected to the substrate; and an actuator comprising a first electrode; a piezoelectric layer over the first electrode; and multiple sets of second electrodes over the piezoelectric layer, wherein each of the sets of second electrodes being defined by a transverse gap there between, and wherein one of the sets of second electrodes are actuated asymmetrically with respect to a first plane resulting in a piezoelectrically induced bending moment arm in a lateral direction that lies in a second plane. The device further comprises an end effector opposite to the anchored end and connected to the actuator; a ferromagnetic core support structure connected to the end effector; a movable ferromagnetic inductor core on top of the ferromagnetic core support structure; and a MEMS inductor coiled around the ferromagnetic core support structure and the movable ferromagnetic inductor core.

Abstract: Kits and methods for building devices for analyzing or suppressing vibrations in equipment are provided. An electrical-mechanical transducer is configured to be placed in operative contact with the equipment. The transducer may be directly mounted to a base plate that is configured for being mounted to the equipment. A first device (e.g., a printed circuit board) carrying electronic componentry is configured for transmitting vibration drive signals to the electrical-mechanical transducer. A second device (e.g., a printed circuit board) carrying electronic componentry is configured for receiving vibration sensing signals from the electrical-mechanical transducer. The first and second devices can be interchangeably mounted within a housing that can be mounted to the base plate. The housing may comprise an aperture for receiving the electrical-mechanical transducer.

Abstract: The present invention relates to a frequency-control-type piezo actuator driving circuit. The frequency-control-type piezo actuator driving circuit includes a piezo actuator that is driven by a constant amplitude of driving voltage pulse; a piezo driver that is connected to the piezo actuator so as to drive the piezo actuator; a frequency controller that is connected to the piezo driver so as to measure currents consumed when the piezo driver drives the piezo actuator, to detect a frequency corresponding to the maximum current among the measured currents, and to generate a frequency control signal corresponding to the detected frequency; and a frequency synthesizer that fixes a frequency of the piezo actuator in accordance with the frequency control signal of the frequency controller and generates the fixed frequency to the piezo driver.

Abstract: A piezoelectric actuator includes: a ring-shaped piezoelectric element, vibration of the piezoelectric element being transmitted to an object; a first vibration area and a second vibration area provided on both sides of a bisector bisecting the piezoelectric element along a diameter of the piezoelectric element, the first vibration area and the second vibration area being respectively provided with at least one drive electrode to which a drive signal is supplied, the drive electrode being arranged substantially axisymmetrically with respect to the bisector, the drive signal including a phase-advance drive signal and a phase-delay drive signal having a predetermined drive phase difference, the phase-advance drive signal that is phase-advanced relative to the phase-delay drive signal being supplied to one of the first vibration area and the second vibration area and the phase-delay drive signal that is phase-delayed relative to the phase-advance drive signal being supplied to the other of the first vibration ar

Abstract: A piezoelectric motor comprising a vibratory element is configured to move a first driven element by vibrations generated by the vibratory element. A second driven element is brought into frictional contact with the first driven element to form a multistage piezoelectric drive system. Alternatively, a selected contacting portion on a support for the first driven element is provided for drivingly engaging the second driven element. The system is configured to also move the second driven element by vibrations generated by the vibratory element, these vibrations being transmitted from the vibratory element into the first driven element and possibly also into the support for the first driven element. The system is preferably configured to move the first and second driven elements independently from each other using only electric signals that are applied to the same one vibratory element.

Abstract: In a piezo-electric motor with alternately electrically actuated clamping piezo packs arranged between a reference part and a drive part and with two stepping piezo packs arranged in an opposite sense and assigned to each clamping piezo pack or to one clamping piezo pack or a support structure, the stepping piezo stacks are connected via quasi-pivotal joint structures to a foot at locations which are spaced from each other in the longitudinal direction of the clamping piezo pack and from the drive part.

Abstract: A vibration wave motor control apparatus which has a simplified construction and is reduced in cost. In a photographic apparatus including a lens, a lens position controller controls the position of the lens using a vibration wave motor driven by a drive voltage of a set frequency, and a drive-frequency controller controls the set frequency. The drive-frequency controller determines an estimated frequency based on a change in the position of a movable unit of the vibration wave motor determined from data inputted from an encoder, and based on the estimated frequency, calculates an updated value of the set frequency and inputs the same to the lens position controller.

Abstract: An electromechanical actuator comprises at least two actuating portions of electromechanically active material extending by a generally elongated shape from a back portion. The actuating portions are bimorphs, attached by a first end to a first side of the back portion and positioned parallel to each other one after the other in a first direction. The bimorphs are arranged to provide movements of the second end along the first direction and along the extension of the actuating portion, thereby being able to move relative a body in the first direction. The actuating portions have generally flat internal electrode layers arranged inside the electromechanically active material directed substantially perpendicular to the first direction. The internal electrode layers extend continuously through the actuating portions and into the back portion.

Abstract: A microelectromechanical system (MEMS) device comprises a substrate; an anchored end connected to the substrate; a free end comprising an end effector opposite to the anchored end; a spring attached to the end effector; multiple actuation beams; multiple connection beams adapted to connect the multiple actuation beams to one another; and an actuator/sensor comprising a first electrode; a piezoelectric layer over the first electrode; and a set of second electrodes over the piezoelectric layer, wherein the set of second electrodes being defined by a transverse gap therebetween. Each of the multiple actuation beams comprises two sets of the second electrodes. The set of second electrodes comprise an extensional electrode and a contraction electrode. One of the sets of second electrodes is actuated asymmetrically with respect to a first plane resulting in a piezoelectrically induced bending moment arm in a lateral direction that lies in a second plane.

Abstract: The present invention is directed to a high-powered (e.g., >500 W) ultrasonic generator for use especially for delivering high-power ultrasonic energy to a varying load including compressible fluids. The generator includes a variable frequency triangular waveform generator coupled with pulse width modulators. The output from the pulse width modulator is coupled with the gates of an Isolated Gate Bipolar Transistor (IGBT), which amplifies the signal and delivers it to a coil that is used to drive a magnetostrictive transducer. In one embodiment, high voltage of 0-600 VDC is delivered across the collector and emitter of the IGBT after the signal is delivered. The output of the IGBT is a square waveform with a voltage of +/?600V. This voltage is sent to a coil wound around the ultrasonic transducer. The voltage creates a magnetic field on the transducer and the magnetorestrictive properties of the transducer cause the transducer to vibrate as a result of the magnetic field.

Abstract: A positioner includes a capacitative element with which an ohmic resistance is connected in parallel. The value of the ohmic resistance is sensed at specific points in time. To enhance operating reliability during operation of the positioner, correct functioning of the ohmic resistance is monitored, and a fault signal is outputted upon detection of a malfunction.

Abstract: The invention relates to precision instrument engineering and can be used in order to create microdisplacements in micron and submicron ranges for cellular microtechnologies (by engineering, gene engineering, reproductive diology and medicine, neurobiology, microphysiology, cytology, etc.), micromechanics and for the electronics and other industries. Said invention is characterized by reduced associated mechanical vibrations of a micromanipulator, high resolution (accuracy), a decreased number of single displacements, the extended speed adjustment range and functional capabilities of the micromanipulator. The inventive micromanipulator comprises a small movable table attached to a drive which is connected to a control unit and embodied in the form of a shaft provided with a rotor which is linked with annular piezoelements by means of pushers. One piezoelement is arranged on the shaft and the second piezoelement on a body.

Abstract: This invention discloses a piezoelectric actuation system used for a nebulizer, and the system includes a frequency generator, a control interface and a piezoelectric actuator. The frequency generator generates at least one electric signal of a frequency value. The control interface is electrically connected to the frequency generator and provided for users to input or select an electric signal of the frequency generator, such that the frequency generator can issue an electric signal of a specific frequency value according to the input or selection of the control interface. Therefore, the piezoelectric actuator can receive the electric signal with the specific frequency value to produce a vibration of the best working frequency.

Abstract: [Problem] A driving circuit of a piezoelectric transformer capable of placing insulation between a primary side and secondary side of each of piezoelectric transformers is provided [Means for solving] In the driving circuit of piezoelectric transformers including piezoelectric transformers 11 to output a specified voltage to cold cathode fluorescent lamps 12, a driving section 50 to apply a voltage V used to drive the piezoelectric transformers 11, a frequency controlling section 51 to control the driving section 50, and a phase detecting section 52 to transmit a detecting signal to the frequency controlling section 51, primary sides of every two out of the piezoelectric transformers 11 are serially connected to one another, making up one pair of piezoelectric transformers 11 and every three pairs of said piezoelectric transformers 11 is connected in parallel to the driving unit and one end portion of each of the cold cathode fluorescent lamps 12 with a same plurality of numbers as for the piezoelectric trans

Abstract: The present invention provides a piezoelectric ultrasonic motor driver which can perform self-oscillation, adjust the rotational direction of the motor, and be easy to manufacture. The motor includes a metal body having a desired shape; a plurality of piezoelectric plates attached to surfaces of the metal body, contracted and expanded to rotate the metal body; a self-oscillation unit for oscillating at an electromechanical frequency of the piezoelectric plates an electrical signal; and a delay unit for delaying an oscillation signal of the self-oscillation unit in phase by 90 or ?90 degrees according to a desired rotational direction.

Abstract: An ultrasonic motor drive device capable of prolong the service life of an ultrasonic motor by preventing the motor from being unstably operated when the motor is driven at a lower speed of at least two speeds. When the ultrasonic motor (3) is driven at a rather low speed in normal driving, the motor can be prevented from being unstably operated by its driving at a rather low speed by driving the motor at a rather high speed for each specified interval. Thus, the service life of the ultrasonic motor can be increased.

Abstract: A fuel injection valve is controlled, the valve includes a piezoelectric actuator as the valve member, which opens up or closes a connection to a space arranged downstream, an electric actuating element for actuating the valve member and a prestressing element which prestresses the valve member into a prestressing direction. A sensor element, which is arranged on the same axis as the valve member supplies an output signal to a control unit concerning the forces acting upon the valve member. The control unit acts upon the actuating element by way of an electric excitation, which has a signal course at least approximately inverse to the output signal of the sensor element.

Abstract: An apparatus comprises a signal source, a driver and an electro-mechanical transducer. The signal source is configured to output a haptic feedback signal. The driver is configured to receive the haptic feedback signal and output a drive signal. The electro-mechanical transducer is configured to receive the drive signal. The electro-mechanical transducer is configured to have a set of operational modes. Each operational mode from the set of operational modes has at least one resonant mode from a set of resonant modes.

Abstract: A method for the electric control of an actuator, especially a piezoelectric actuator of an injection system comprises the following steps: charging the actuator; waiting during a specific period of time (D1, D2) and discharging the actuator after the expiration of the period of time (D1, D2). The period of time (D1, D2) is variably determined in order to compensate the quantization steps.

Abstract: A mechanical quantity sensor includes a current-to-voltage converter/signal adder circuit that converts electric current signals flowing through two piezoelectric vibrators into voltage signals. The piezoelectric vibrators receive stresses generated by a mechanical quantity, such as acceleration, in opposite directions. A voltage amplifier/amplitude limiter circuit amplifies an added signal obtained from the two voltage signals and limits its amplitude. A phase-difference-to-voltage converter circuit detects a difference in the phases of the added signal and a feedback voltage signal applied to an acceleration detection element. A phase shifter circuit controls the phase of the feedback voltage signal so that the phase is a predetermined phase. A filter circuit minimizes frequency components higher than an oscillation frequency in an unwanted frequency band. By increasing the resistance of resistors so as to increase the damping ratio, temperature stability is increased.

Abstract: An ultrasonic transducer including: a fixed electrode; a vibrating film placed opposite to a surface of the fixed electrode and having a conducting layer; a member that holds the fixed electrode and vibrating film; the fixed electrode including a driving-use fixed electrode formed to drive the ultrasonic transducer, and a detecting-use fixed electrode formed to detect an amplitude of the vibrating film; and a unit that controls a signal to be applied to the driving-use fixed electrode based on a magnitude of the amplitude of the vibrating film detected by the detecting-use fixed electrode so that the magnitude of the vibration of the vibrating film becomes in proportion to an input signal, wherein when an alternating current signal is applied between the fixed electrode and the conducting layer of the vibrating film, the ultrasonic transducer generates an ultrasonic wave.

Abstract: A method of producing an actuator includes shaping a block of ferroelectric material to provide an active element of the actuator. The element includes a stack of ferroelectric layers with adjacent layers separated by electrodes arranged parallel to end faces of the element. The method includes applying a primary electrode to the end faces, immersing the element and the primary electrode within a dielectric fluid, applying a primary poling voltage to the primary electrode so as to polarize the element in a first polarization direction, applying a secondary external electrode to side faces of the element, and applying a secondary poling voltage to the secondary electrode to polarize alternate layers along the first polarization direction and the other layers along a second, oppositely-directed polarization axis. The method may also include applying a conductive film to the end faces and/or applying heat to help evaporate the dielectric fluid.

Abstract: The system controls the frequency of an ultrasonic signal to be applied to a waveguide, such that the frequency corresponds to a preferred resonance mode of the waveguide and not to adjacent undesirable resonance modes. The system operates by carrying out a first scan of a predetermined portion of the generated signal, determining the number of resonance modes of the waveguide within this portion and selecting from these resonance modes either that one mode which is at a central frequency or that one mode which is at a frequency nearest thereto. The system may also set limits on each side of the selected resonance mode and carry out a second scan within these limits each time that the generator is activated to check whether the selected resonance mode is drifting.

Abstract: A transconductance monitoring and amplifying circuit for a piezoelectric transducer that may be used in, e.g., a motion detector system includes a FET, with the transducer (and, hence, the signal voltage reference) floating between the gate and source of the FET, as opposed to being connected to the common ground of the circuit. This permits the development of a larger detector signal and concomitantly the use of a relatively inexpensive FET instead of a relatively more expensive high impedance operational amplifier as must be used in conventional transconductance circuits. The FET and transducer can be held in a single four-pin package. A discrete time sampled operational amplifier may also be used.

Abstract: A piezoactuator has a diaphragm, and the diaphragm has flat piezoelectric elements that oscillate in a longitudinal oscillation mode and a sinusoidal oscillation mode. A first electrode for detecting oscillation in the longitudinal oscillation mode, and a second electrode for detecting the amplitude of oscillation in the sinusoidal oscillation mode, are disposed on the surface of the diaphragm. When the piezoactuator is driven with a drive signal, the phase difference of a first detection signal output from the first electrode and a second detection signal output from the second electrode is detected. The frequency at which the detected phase difference becomes the maximum phase difference is then obtained, and a drive signal of a matching frequency is applied to the piezoelectric elements.