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Showing papers on "Transducer published in 1986"


Patent
01 Aug 1986
TL;DR: An ultrasonic apparatus for testing a material comprises an oscillator (10) which generates a selected frequency in the ultrasonic range, and a transducer (1) is connected to the oscillator for applying an ultrasonic signal to the material and for receiving an echo signal back from the material.
Abstract: An ultrasonic apparatus for testing a material comprises an oscillator (10) which generates a selected frequency in the ultrasonic range. A transducer (1) is connected to the oscillator (10) for applying an ultrasonic signal to the material and for receiving an echo signal back from the material. A phase detector (5) receives the echo signal and an in-phase oscillator signal to generate a first display signal, and a phase detector (6) receives a quadrature signal (90° out of phase from the oscillator signal) and the echo signal to generate a second display signal. The first and second display signals are utilised in a visual display, such as a cathode ray tube (8), to generate an image. The image changes according to the phase shift between the ultrasonic signal transmitted into the material and the echo signal, which, in turn, can be utilised to determine the presence and depth of a flaw or boundary in the material.

1,017 citations


Patent
19 May 1986
TL;DR: In this article, an endoscopic ultrasonic transducer was used to extract compliant biological tissue from the intracellular fluids in the tissues to achieve maximum cavitation of the fluids.
Abstract: A method and apparatus for endoscopic removal of compliant biological tissues utilizing an endoscopic ultrasonic aspirator comprising irrigation and aspiration means, a piezoelectric ultrasonic transducer, a first resonator such as a half-wave stepped velocity transformer, a probe including a second resonator such as a constant-stress velocity transformer, a blunt or modified working tip of open channel means or restricted tubular means for application of ultrasonic energy to cellular material, and a capacitive fluid sensor to detect the presence of irrigation fluid adjacent these transformers within the instrument. The surgery is advantageously performed by operating the transducer in the 10-20 kHz range to achieve maximum cavitation of the intracellular fluids in the tissues to be removed.

776 citations


PatentDOI
TL;DR: In this paper, an ultrasonic transducer is carried by the distal end of a catheter adapted for insertion into a vessel, and either the transducers or another element is rotated and/or translated relative to the catheter to image different portions of the vessel.
Abstract: Ultrasonic apparatus, system and method for high resolution intravascular imaging to assist indovascular lesions and to monitor the results of interventional therapy. An ultrasonic transducer is carried by the distal end of a catheter adapted for insertion into a vessel, and either the transducer or another element is rotated and/or translated relative to the catheter to image different portions of the vessel.

475 citations


Journal ArticleDOI
TL;DR: The use of an auxiliary random noise generator for this modeling is described, which is easy to implement, provides continuous on‐line modeling, and has minimal effect on the final value of the error signal.
Abstract: Active sound attenuation systems may be described using a system identification framework in which an adaptive filter is used to model the performance of an unknown acoustical plant. An error signal may be obtained from a location following an acoustical summing junction where the undesired noise is combined with the output of a secondary sound source. In order for the model output to properly converge to a value that will minimize the error signal, it is frequently necessary to determine the transfer function of the secondary sound source and the path to the error signal measurement. Since these transfer functions are continuously changing in a real system, it is desirable to perform continuous on‐line modeling of the output transducer and error path. In this paper, the use of an auxiliary random noise generator for this modeling is described. Based on a Galois sequence, this technique is easy to implement, provides continuous on‐line modeling, and has minimal effect on the final value of the error signal.

304 citations


PatentDOI
TL;DR: In this article, an annular array ultrasound transducer, a mechanical driver, a transmitter/receiver, and a controller are used to change at least one of the position and direction of ultrasound beams transmitted and received by the transducers.
Abstract: An ultrasound therapy system comprises an annular array ultrasound transducer, a mechanical driver, a transmitter/receiver, and a controller. The controller includes an imaging controller, a heating controller, and a select controller. The mechanical driver mechanically drives the transducer to change at least one of the position and direction of ultrasound beams transmitted and received by the transducer. The transmitter/receiver may supply drive signals to the respective elements of the transducer, and receive the ultrasound echo signals from the elements. The imaging controller gives a first drive command to the transmitter/receiver, and at the same time drives the mechanical driver, radiates scanning ultrasound beams for tomographing through the transducer, and obtains a tomogram of a target portion in a patient from the echo signal derived from the transmitter/receiver. The heating controller drives the transmitter/receiver by a second drive signal to cause the transducer to radiate heating ultrasound beams. The heating ultrasound beams heat the target. These imaging and heating controllers are selectively activated by the select controller.

270 citations


Patent
15 Aug 1986
TL;DR: In this article, the flying height of a magnetic transducer slider is calculated as the ratio, expressed in decibels, of the first and second signals times the wavelength divided by a constant.
Abstract: A method and apparatus for measuring the flying height of a slider supporting a magnetic transducer in-situ in a direct manner in an operational magnetic disk storage system. The method and apparatus produce relative motion between the magnetic transducer and a magnetic recording medium at a first velocity so that the resulting air bearing positions the magnetic transducer slider at a first flying height from the magnetic medium. A single signal of constant periodicity is written over a predetermined area of the recording medium by the magnetic transducer, and a readback signal is sensed from the predetermined area of the recording medium to produce a first signal. The flying height of the magnetic transducer slider is lowered to substantially zero, and a readback signal is sensed at the lowered flying height to produce a second signal. The first flying height is then calculated as the ratio, expressed in decibels, of the first and second signals times the wavelength divided by a constant. In an alternate embodiment a plurality of signals are recorded and readback signals are simultaneously sensed at two separate wavelengths. In a further embodiment, a signal is recorded which has a spectral content comprising a plurality of different frequencies, and readback signals are simultaneously sensed at two separate wavelengths.

213 citations


PatentDOI
TL;DR: In this paper, an accelerometer transducer has a base holding a sheet normal to an input axis, suspended from the base by a first spring arrangement for oscillatory motion in the way of limited angular excursions about a central axis lying in the sheet.
Abstract: An accelerometer transducer has a base holding a sheet normal to an input axis. The sheet is suspended from the base by a first spring arrangement for oscillatory motion in the way of limited angular excursions about a central axis lying in the sheet. A weight is spring-suspended from the sheet in a manner permitting displacement of the center of gravity of the weight along the input axis. Acceleration along the input axis varies the moment of inertia of the assembly consisting of the sheet and the weight about the central axis, altering the frequency of oscillatory motion by an amount functionally related to the magnitude of the acceleration. The sheet is driven at its characteristic frequency, and its frequency of oscillation is measured. In a preferred embodiment, a first transducer includes a weight suspended offset from the sheet in a first direction along the input axis, and a second transducer includes a weight offset from the sheet in the opposite direction along the input axis. The change of oscillatory frequency of the second transducer is subtracted from that of the first transducer to develop an output quantity linearly related to the acceleration. In a preferred embodiment, the sheets, springs and weights are micromechanical devices fabricated by semiconductor fabrication techniques. Electrostatic driving elements for driving the sheet, and a capacitive pick-off for sensing its vibration are also shown.

148 citations


Patent
27 Aug 1986
TL;DR: In this paper, an endoscopic ultrasonic transducer was used to extract compliant biological tissue from the intracellular fluids in the tissues to achieve maximum cavitation of the fluids.
Abstract: A method and apparatus for endoscopic removal of compliant biological tissues utilizing an endoscopic ultrasonic aspirator comprising irrigation (94) and aspiration (122) means, a piezoelectric ultrasonic transducer (70), a first resonator (72) such as a half-wave stepped velocity transformer, a probe including a second resonator (78) such as a constant-stress velocity transformer, a blunt or modified working tip (80) of open channel means or restricted tubular means for application of ultrasonic energy to cellular material, and a capacitive fluid sensor (124) to detect the presence of irrigation fluid adjacent these transforms within the instrument. The surgery is advantageously performed by operating the transducer in the 10-20 KHz range to achieve maximum cavitation of the intracellular fluids in the tissues to be removed.

147 citations


PatentDOI
TL;DR: In this article, the authors present a system for spatial location and destruction of concretions in bodily cavities by application of pulsed ultrasonic shock waves generated by a shock wave transducer focussed on the concretion in question, the shock waves being transmitted to the patient by coupling fluid.
Abstract: A device for spatial location and destruction of concretions in bodily cavities by application of pulsed ultrasonic shock waves generated by a shock wave transducer focussed on the concretion in question, the shock waves being transmitted to the patient by a coupling fluid. This transducer may also be operated under reduced power if appropriate during the locating operation, as an A-scanner, according to the pulse echo mode. A B-section image of the bodily tissue traversed by the ultrasonic field is generated on a monitor by means of at least one B-scanner, so that the concretion present in the section image may be placed in coincidence with a target mark present on the monitor and indicating the position of the transducer focus by a relative displacment between the patient and the device, and the shock wave transducer may thereafter be placed in operation under corresponding high power for destruction of the concretion. A support carrying the B-scanner is displaceable with respect to the symmetry axis of the shock wave transducer during the locating operation, so that it is possible to have a plurality of different section images and thus a high degree of spatial resolution of the section scanned during the locating operation.

132 citations


PatentDOI
TL;DR: In this paper, a direct contact hearing aid is described, including an output electromechanical transducer for converting audio output signals into mechanical movement of an output coupling element without the production of discernible sound waves to prevent acoustic feedback.
Abstract: A direct contact hearing aid apparatus adapted to be mounted deep within the ear canal is disclosed, including an output electromechanical transducer for converting audio output signals into mechanical movement of an output coupling element without the production of discernible sound waves to prevent acoustic feedback. The coupling element is supported for magnetic engagement with a contact element mounted on the tympanic membrane by a metal clip attached to the malleus bone to provide direct electromechanical coupling to the ossicles through the tympanic membrane. Alternatively, the contact element may be attached to the malleus bone by a clamp whose jaws are lined with bioactive ceramic. A pair of magnetic switches is provided within the hearing aid housing for mechanically switching the connections of the battery and a volume control while the hearing aid is mounted in the ear canal in response to changes in the polarity of a remote external magnetic actuator located outside of the housing. An external magnetic attachment device is used for insertion and removal of the hearing aid, radio or other electronic apparatus into and from the ear canal by magnetic engagement with a magnetic holder member on the electronic apparatus. The magnetic attachment device may be unipolar or bipolar and has a permanent magnet which is rotated between an attraction position and a release position by a selection knob. The output transducer of the hearing aid may be a piezoelectric plastic film transducer in the form of a flexible diaphragm or a folded sheet bender of the bimorph type, or it may be an electromagnetic transducer. The electromagnetic transducer may have an external magnetic coupling element mounted outside the hearing aid housing and spaced from the magnetic core of such transducer but coupled to the contact element. Also, a reverse bias permanent magnet may be provided at the end of such core to repel a movable permanent magnet which is mounted on a resilient coupling member to form the external magnetic coupling element.

128 citations


Patent
08 Sep 1986
TL;DR: In this article, a transducer is mounted on a target pad and provides an analog output indicative of the characteristic of an object impacting the target pad, i.e., baseball, softball, tennis ball, hockey puck, golf ball etc.
Abstract: Disclosed is a device for generating an analog output signal indicative of an impact to a transucer. The tranducer may be mounted on protective equipment utilized in various martial arts fields, such as headgear, hand or footgear, protective vests and the like or can be mounted on training equipment, such as a heavy bag, striking pad, etc. In a preferred embodiment the transducer is a piezoelectric film which, upon deformation, generates an electrical signal which is indicative of the amount of deformation. By placing the piezoelectric film on top of a deformable material, in a preferred embodiment sandwiching it in the deformable material, impacts to the deformable material will strain the piezoelectric film generating the signal output. In a further embodiement of the present invention, the piezoelectric transducer is mounted on a target pad and provides an analog output indicative of the characteristic of an object impacting the target pad, i.e., baseball, softball, tennis ball, hockey puck, golf ball, etc. For use in the martial arts, the transducer may be connected to a transmitter and remote receiver for providing an indication of the impact at a remote location. In further preferred embodiments, the transucers may be mounted on one participant's headgear so as to provide an indication of impacts delivered to that participant by another participant in the sport or mounted on the hands or feet of the participant to provide a signal by means of a flexible transducer mounted on the hand or foot, thus providing an indication of a flow delivered to another party.

Patent
25 Mar 1986
TL;DR: In this article, a piezoelectric transducer was used to measure the total energy spent in motion by the human body, and the desired body energy spent can be displayed quantitatively by first converting the integrated signal into a pulse train, then counting the pulses, and then driving a display with the counter's value.
Abstract: Clamping a piezoelectric transducer onto the arm produces a signal whose integration with respect to time corresponds directly to the energy produced by the arm's movement. By clamping four (4) such transducers onto the body, one on each arm and one on each leg, the total integration of the four (4) signals gives a measure of the total energy spent in motion by the body. The desired body energy spent can be displayed quantitatively by first converting the integrated signal into a pulse train, then counting the pulses, and then driving a display with the counter's value.

Patent
22 Dec 1986
TL;DR: In this article, an electromagnetic transducer is proposed for self-propelled vehicle applications such as passenger cars, which can utilize a shell construction, which enhances heat removal, and includes a magnetic flux producing assembly, having a plurality of spaced magnetic elements.
Abstract: An electromagnetic transducer is disclosed that is lightweight and has a high power to weight ratio, with the transducer being capable of operation as an efficient motor, alternator or generator, and being particularly useful, for example, in connection with self-propelled vehicle applications such as passenger cars. The electromagnetic transducer can utilize a shell construction, which enhances heat removal, and includes a magnetic-flux producing assembly, having a plurality of spaced magnetic elements, and an armature assembly formed by a winding arrangement of dispersed conductive elements which are separated by flux carrying elements which, to the extent that such flux carrying elements are electrically conductive, are dispersed in one, two, or three dimensions to thus be dispersed-phase flux carrying elements. The armature conductors and flux carrying elements are dispersed to minimize creation of opposing induced currents, or eddy currents, depending on the effect produced on transducer operation. This dispersal enables operation of the transducer at high efficiency with high torque being maintained even during high speed relative motion between the magentic flux producing assembly and the armature with the combination of high torque and high speed producing higher power per unit weight than can now know devices.

PatentDOI
TL;DR: In this paper, a transducer is pivoted by a linear motor having an electrical coil as the reciprocally moving member, which is in a plane orthogonal to the lines of magnetic flux between opposed permanent magnets of opposite polarity affixed to the probe case.
Abstract: A transducer is pivoted by a linear motor having an electrical coil as the reciprocally moving member. The coil is in a plane orthogonal to the lines of magnetic flux between opposed permanent magnets of opposite polarity affixed to the probe case, providing efficiency. A mechanical linkage between the linear motor electrical coil moving member and the transducer which is forced in pivoting motion transmits only axial force, and not torque, by employing a ball and socket joint at one end of a crankshaft. Electrical connections to the electrical coil are facilitated through springs which additionally mechanically bias the reciprocal movement of the coil. Electrical connections to the pivoting transducer are facilitated through a helical coil wrapping the pivot shaft. These electrical connections accomodate mechanical motions within the probe. A bellows-fold cylindrical air bladder is positioned within the fluid chamber of the probe to allow for thermally-induced changes in fluid volume.

Patent
Mersch Steven H1
29 Oct 1986
TL;DR: In this paper, an optical fiber transducer system with energy generating means for transmitting pulsing energy at various frequencies to bidirectional couplers for each frequency is described.
Abstract: Disclosed in an optical fiber transducer system with energy generating means for transmitting pulsing energy at various frequencies to bidirectional couplers for each frequency. The couplers record the intensity and further transmit the pulsing energy to a wavelength multiplexer/demultiplexer. The wavelength multiplexer/demultiplexer combines the plurality of energy supply means into a single output for an optic fiber which includes an optical delay sufficient to time separate the pulsing waves of energy. Reflected energy is transmitted back through the same wavelength multiplexer/demultiplexer, bidirectional coupler so that the recorded intensity of transmission and reflectance are comparable without system influence. A method is also shown for use of an optical fiber system including the components set forth and the system requires the generation and combination of the various frequencies of energy in a multiplexer/demultiplexer, the delay for time separation and the detection in a bidirectional coupler of transmitted and reflected energy.

Patent
Haruyasu Rokurota1
14 Aug 1986
TL;DR: In this paper, the ultrasonic transducers are formed on planes of a plate-shaped piezoelectric element to provide an ultrasonic Transducer material, which is bonded to an electrically insulating substrate by electrically conductive adhesive.
Abstract: Electrode layers are formed on planes of a plate-shaped piezoelectric element to provide an ultrasonic transducer material. The ultrasonic transducer material is bonded to an electrically insulating substrate by electrically conductive adhesive. A plurality of conductors is provided on the substrate in the array direction and a direction perpendicular to the array direction. A printed circuit is formed on the backside of the substrate to connect the conductors. Notches are cut out in the ultrasonic transducer material to divide it into a plurality of transducer elements arranged in the array direction and a direction perpendicular to the array direction. A ground electrode connects the second electrodes of the ultrasonic transducer elements. The transducer elements are impressed with voltage through the printed circuit and ground electrode to issue ultrasonic waves.

Patent
03 Nov 1986
TL;DR: A timepiece includes a variable color display for indicating time in digital format and a physical transducer for measuring values of a physical quantity as discussed by the authors, and the color of the display may be controlled in a plurality of steps in accordance with the output of the physical transducers.
Abstract: A timepiece includes a variable color display for indicating time in digital format and a physical transducer for measuring values of a physical quantity. The color of the display may be controlled in a plurality of steps in accordance with the output of the physical transducer.

Journal ArticleDOI
John K-J. Li1
TL;DR: A simple, fast time domain method for the resolution of aortic pressure and flow pulses into their forward and reflected components is presented.
Abstract: A simple, fast time domain method for the resolution of aortic pressure and flow pulses into their forward and reflected components is presented. Accuracy of the method depends on the estimation of characteristic impedance and the frequency responses of the transducer systems.

Patent
16 Oct 1986
TL;DR: A timepiece includes a variable color multi-element display for indicating time in digital format and a plurality of transducers associated with respective display elements as mentioned in this paper, and the color of each display element may be independently controlled, either in a pluralityof steps or substantially continuously, in accordance with the output of its associated transducers.
Abstract: A timepiece includes a variable color multi-element display for indicating time in digital format and a plurality of transducers associated with respective display elements. The color of each display element may be independently controlled, either in a plurality of steps or substantially continuously, in accordance with the output of its associated transducer.

PatentDOI
TL;DR: In this paper, an ultrasonic transducer transmits a ultrasonic pulse in response to the drive signal and develops an echo signal upon receipt of an echo pulse derived from the ultrasonic pulses; a shunt switch is connected across a winding of the transformer and is selectively closed to quickly damp the ringing following the transmission of ultrasonic signals to a level substantially below the level of the echo signal.
Abstract: An ultrasonic ranging system includes transformer means with a transformer which is selectively energized to produce a transducer drive signal. An ultrasonic transducer transmits an ultrasonic pulse in response to the drive signal and develops an echo signal upon receipt of an echo pulse derived from the ultrasonic pulse; a shunt switch is connected across a winding of the transformer and is selectively closed to quickly damp the ringing following the transmission of an ultrasonic pulse to a level substantially below the level of the echo signal to permit close ranging.

Journal ArticleDOI
TL;DR: In this paper, the mechanical impulse response of a piezoelectric transducer has been plotted by using an optical interferometric heterodyne probe, which is better than 10−4 A/(Hz)1/2.
Abstract: The mechanical impulse response of a piezoelectric transducer has been plotted by using an optical interferometric heterodyne probe. The sensitivity of this Mach–Zehnder type probe is better than 10−4 A/(Hz)1/2. Transient displacements of a few angstroms have been detected in a single sweep with a 20‐MHz bandwidth.

Patent
18 Jun 1986
TL;DR: In this article, a pressure transducer is mounted on a carrier plate and integral extensions of the electrical output connections pass through holes in the carrier plate, and a housing for the sensor assembly has an opening therein to provide access to the diaphragm by ambient atmosphere/fluid.
Abstract: A pressure sensor assembly includes a pressure transducer having a pressure displaceable diaphragm bonded to a base. Displacement of the diaphragm results in varying of electrical characterisitcs of the transducer in response to sensed pressure. Electrical output connections (wires) of the transducer extend from a central portion of a top surface of the base, which faces the diaphragm, to a central portion of a base bottom surface and peripheral portions of the diaphragm and base top surface are hermetically bonded together. The transducer is mounted on a carrier plate and integral extensions of the electrical output connections pass through holes in the carrier plate. A housing for the sensor assembly has an opening therein to provide access to the diaphragm by ambient atmosphere/fluid surrouding the housing. A first inner seal bonds at least the peripheral portions of the base bottom surface to the carrier plate, and a second outer seal is positioned between the carrier plate top surface and walls of the housing. The housing walls, carrier plate and first and second seals form an effective seal against ambient atmosphere/fluid which contacts the diaphragm and, therefore, seal and protect the electrical output connections of the transducer. The housing walls form an internal cavity which is isolated from the sensed ambient atmosphere/fluid. Within the internal cavity components are connected to the extensions of the clectrical output connections which pass through the carrier plate holes.

Patent
04 Mar 1986
TL;DR: In this article, a pressure sensor implanted into the skull to emit an electrical signal representing the intra-cranial pressure is described, which is of the type which includes on one hand a test body comprising a deforming diaphragm and of an undeforming guard ring.
Abstract: The invention relates to a pressure sensor implanted into the skull to emit an electrical signal representing the intra-cranial pressure; this sensor is of the type which includes on one hand a test body (1) comprising a deforming diaphragm (3) and of an undeforming guard ring (2), and on the other hand a deformation detector (5) associated with the diaphragm; the test body (1) is made of an integral piece, in particular plastic, and has a continuous front side (1a) which preferably is planar; the mechanical and dimensional properties of the constituent plastic are matched in such a manner that under the maximum pressure of 30 kilopascals, the diaphragm deflection is within a predetermined range; within this range, the dura mater pressed by the sensor transmits faithfully the intracranial pressure with adequate sensitivity to employ a resistive type transducer which simultaneously is simple, rugged compact and economical.

PatentDOI
TL;DR: In this paper, an ultrasonic sensor system particularly for automatic door openers of a swinging door type, in addition to sensors for people approaching a door for controlling opening and closing purposes, has at least three microprocessor controlled ultrasonic beam transducers (40, 41, 42) for projecting expanded unidirectional ultrasonic beams in a selected directions in a detection zone in the path of the swinging door and ultrasonic detector for converting reflected single multiple path ultrasonic energy into an analog electrical signal which constitute an acoustical image of objects in and bounding the selected detection
Abstract: An ultrasonic sensor system particularly for automatic door openers of a swinging door type, in addition to sensors (14) for people approaching a door for controlling opening and closing purposes, has at least three microprocessor controlled ultrasonic beam transducer (40, 41, 42) for projecting expanded unidirectional ultrasonic beams in a selected directions in a detection zone in the path of the swinging door and ultrasonic detector for converting reflected single multiple path ultrasonic beam energy into an analog electrical signal which constitute an acoustical image of objects in and bounding the selected detection zone. This acoustical image is stored or, a number characteristic thereof is stored and this acoustic image is then compared with a later acoustical image of an object in the selected detection zone and then the comparison is used to signal a lack of correlation between the first and second acoustical images to produce a signal preventing operation of the door opening. In a preferred embodiment, aspect ambiguities and problems of acoustic "transparency" are avoided by using direct multiple path reflections of three or more ultrasonic beam transducers projecting crossing beams and which have their signals multiplexed, controlled, and processed by a single computer microprocessor chip.

Journal ArticleDOI
TL;DR: In this article, a comparison of capacitive and other types of pressure transducers is presented, and the capacitive measurement circuits that determine the overall performance of the transducers are reviewed, with examples to illustrate the achievable characteristics.

PatentDOI
TL;DR: In this article, an arrangement for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder, was disclosed, where an inductive loop, formed by at least one turn of an electrical conductor, is connected to the two input/output terminals of the SAW device.
Abstract: An arrangement is disclosed for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder. The SAW device has two input/output terminals electrically connected to at least one transducer for converting between electrical energy and SAW energy. Such transducer presents to the terminals a prescribed capacitance in the frequency range of operation. An inductive loop, formed by at least one turn of an electrical conductor, is connected to the two input/output terminals of the SAW device. The inductance of the loop is made substantially equal to the prescribed capacitance at the frequency range of operation, thus forming a resonant circuit with the SAW device. The loop also forms a protective DC short circuit across the two terminals, preventing build-up of static electricity. The inductive loop is inductively coupled to an antenna capable of receiving and/or transmitting radiation in the frequency range of operation.

Patent
09 Apr 1986
TL;DR: In this article, a monolithic array ultrasonic transducer has a plurality of transducers formed thereon by isolating metallized areas on a piezoelectric plate.
Abstract: A monolithic array ultrasonic transducer has a plurality of transducer elements formed thereon by isolating metallized areas on a piezoelectric plate without cutting the piezoelectric plate apart for each transducer element, and an acoustic matching layer having a longitudinal wave velocity within ±25% of a longitudinal wave velocity of the piezoelectric plate and a thickness equal to one half of that of the piezoelectric plate. The acoustic matching layer suppresses the radiation to an object of a partial wave in a direction of 60° to a normal line to the plane of the piezoelectric plate.

Journal ArticleDOI
D. Barry1, A. M. Ahmed1
TL;DR: The basic features of a modified buckle transducer for the direct in-situ measurement of tension in ligamentous or tendonous tissues are described and its performance characteristics are described.
Abstract: The basic features of a modified buckle transducer for the direct in-situ measurement of tension in ligamentous or tendonous tissues are described. The slender shape of the modified design allows measurement in ligaments located in confined spaces with reduced risk of physical interference between the transducer and adjacent bony structures. In addition, simultaneous measurements in different fiber groups of the same ligament are made convenient. The design procedure of the proposed transducer and its performance characteristics are described.

PatentDOI
TL;DR: In this paper, a bone containing body member is placed between a pair of transducers and a predetermined sequence of tone signals having frequencies spanning a range from 200 to 600 kilohertz is transmitted through the body member, and the set of values representing the amplitudes of the corresponding received signals are stored.
Abstract: In the apparatus disclosed herein, a bone containing body member to be tested is placed between a pair of transducers and a predetermined sequence of tone signals having frequencies spanning a range from 200 to 600 kilohertz is transmitted through the body member, and the set of values representing the amplitudes of the corresponding received signals are stored. The set of values obtained with the body member between the transducer is normalized using a set of values obtained from the same sequence without the body member in place thereby to generate a third set of values which are compensated for the response characteristics of the transducer and related interfaces. A value corresponding to the rate of change of attenuation with respect to frequency is then calculated from the third set of values and is adjusted for the bone thickness, this adjusted value being related to characteristics of the body member. The bone thickness is determined by a broadband pulse echo measurement.

PatentDOI
TL;DR: A transducer for a musical instrument through which vibrations can be fed back to the instrument so that notes played on the instrument can be sustained is described in this article, where the transducers are attached to a surface of a sheet opposite the surface of the sheet to which the permanent magnetic poles are attached.
Abstract: A transducer for a musical instrument through which vibrations can be fed back to the instrument so that notes played on the instrument can be sustained. The transducer comprises a bracket for mounting the transducer to the instrument. First and second opposited permanent magnetic poles project away from the bracket. A first surface of a sheet of non-magnetic, non-electromagnetic resilient material is attached to the projecting first and second magnetic poles. An electromagnetic core has a spine and first and second legs originating at, and extending away from, the spine and terminating at first and second end faces, respectively. The first and second end faces are attached to a surface of the sheet opposite the surface of the sheet to which the permanent magnetic poles are attached, with the first face adjacent the first permanent magnetic pole and the second face adjacent the second permanent magnetic pole. A conductor is wound on the core. Varying current flow in the conductor induces flux variations in the core.