Showing papers on "Transducer published in 1975"

Effect of transducer placement on echocardiographic measurement of left ventricular dimensions.

Abstract: An echocardiogram from the left ventricle may be used to estimate left ventricular volume and rate of circumferential fiber shortening, to measure posterior wall and interventricular septal thickness and to evaluate the normality of septal motion. Extended application of this technique in this laboratory has emphasized the need for a more standardized means of transducer location and direction. The effect of placing the ultrasonic transducer in several intercostal spaces along the left sternal border was tested in 14 patients. Variability in the left ventricular dimension and the difference in this dimension from end-diastole to end-systole were greater than for duplicate measurements from the same interspace. A system has been developed for more consistent placement of the transducer in each patient, using intracardiac landmarks and observation of transducer orientation to record specific cardiac structures.

Miniature pressure transducer for medical use and assembly method

Abstract: A fluidtight, hermetically sealed, miniature transducer adapted to be inserted into the human body and useful for directly monitoring internal fluid or pneumatic pressures within the human body is disclosed. Semiconductor strain gauge elements constituting a piezoresistive bridge are formed by diffusion on the surface of one side of an integral flexible, rectangular, silicon diaphragm area of a single crystal silicon base. A single crystal silicon cover is eutectically bonded to the base by a metallic laminate seal. The base, cover, and seal define an evacuated fluidtight chamber containing the strain gauge elements. Electrical conductors, which include diffused conductor paths under an insulating oxide layer, extend from the piezoresistive bridge to contact pads outside the fluidtight chamber. The contact pads can be connected to a readout device for electrically measuring the pressure differential between the evacuated chamber and fluid external to the transducer as a function of time.

Surface Acoustic Wave Multielectrode Transducers

Abstract: In the basic SAW transducer, the fingers are connected alternately to the two bus-bars. Interesting responses can be ob- tained if there are more than two fingers per fundamental acoustic wavelength, and the fingers are connected to the bus-bars in various ways. Several of these structures are discussed qualitatively. The transmission spectra obtained from these various schemes are con- firmed experimentally. Quantitative calculations of admittance are also performed for several transducer structures. The measured data agree well with calculations.

Ultrasonic imaging method and apparatus

Abstract: The ultrasonic imaging method and apparatus comprises an ultrasonic wave transducer supplied with recurrent multifrequency energy pulses for pulse insonification of an object under investigation with ultrasonic waves. Resultant echo waves from the object are directed onto the transducer for converting the same to electrical signals which are supplied to a signal processor which includes a variable bandpass filter. One or more of the filter characteristics are varied as a function of depth from which the echo signals are returned for enhanced resolution and signal-to-noise ratio of the received signal. Preferably, the filter is matched to the noise and signal spectra of the system. For A scan and B scan operations wherein reverberated acoustic pulses are derived from a range of depths a time variable filter is employed for time varying operation thereof.

Ultrasonic scanning system with video recorder

Abstract: An ultrasonic scanning system for observing the internal organs of the body including at least one ultrasonic transducer for sequentially scanning a region of the body and pulsing means for periodically pulsing said transducer as it begins a scan. Video recording means records a composite signal including scanning, pulse rate and echo information for reproduction. Display means are included for directly displaying the information or for displaying the play-back from the video recorder. The display is interlaced, providing minimum jitter and maximum resolution.

Acoustooptic scanner apparatus and method

Abstract: An apparatus and method for laser-beam modulation and deflection wherein stored information is recorded on a photosensitive or other recording medium with a laser or other light beam. A plurality of separate frequencies is induced by a transducer on an acoustooptic light-modulating cell which carries and develops every frequency separately. The light beam is passed through the acoustooptic cell which modulates the light by Bragg reflection in accordance with the frequencies impressed thereon. The modulated light beams transmitted from the cell are used to record by a plurality of simultaneous scans, characters, graphical data or other form of information which is representative of the stored information on the photosensitive medium.

Receiver system for receiving audio electrical signals

Abstract: A receiver system includes means for electromagnetically coupling audio bandwidth information signals from an induction loop to a miniature induction receiver/transducer. The induction loop is shaped to be worn around the neck of a wearer. The receiver/transducer is physically shaped for placement in the mouth of the wearer. In response to the varying magnetic induction field generated by the induction loop, the audio bandwidth information signals are amplified by the receiver and converted into substantially linear mechanical movement by the transducer. The output of the transducer is propagated mechanically, directly to the inner ear mechanism, via the teeth and gums of the wearer whereby the wearer perceives the message content of the audio bandwidth information signals without the use of conventional outer ear mechanism.

Ultrasonic measuring system with isolation means

Abstract: A device for performing ultrasonic measurements on liquid flowing within a conduit having walls of relatively high acoustic impedance material. The conduit is split into two separate segments with the emitting transducer in one segment and a receiving transducer in the other segment. The space between segments is filled with a sealant material having relatively low acoustic impedance characteristics to provide an acoustic mismatch and hence attenuation to ultrasonic energy traveling through the conduit wall from the transmitter to the receiver. Because of the separation between segments ready access is provided to the internal walls of the conduit, allowing transducer configurations to be employed, which configurations require machining or assembly to be performed on the interior walls.

Ultrasonic pulse-echo apparatus

Abstract: For use in ultrasonic pulse-echo apparatus including an ultrasonic wave transducer for transmitting an ultrasonic wave toward an object to be examined and for producing an electric signal corresponding to echo pulses reflected by the object, an improved signal processing circuit for compensating for attenuation effects caused by ultrasound absorption, diffraction, reflection and scattering. Compensation for these image-degrading effects assures simple, reliable and repeatable equipment performance, and contributes to reliable detection of very weak echoes.

Electrostatic position-measuring transducer

Abstract: Two relatively movable, spaced elements having electrostatically coupled sets of uniformly spaced interdigitated electrodes form a precision, high gain linear or angular position-measuring transducer. Coupling electrodes on one element capacitively couple to portions of the electrodes on the other element so that electrical connections to external excitation and detection circuitry need be made to only one of the two elements. The shape and dimensions of the electrodes can be arranged to reduce or eliminate undesired impedance variations, capacitive coupling and unwanted harmonic coupling wave frequency components.

Fluid flow measurement system for pipes

Abstract: A plurality of transducers are positioned in the walls of a pipe conveying a fluid, the volumetric flow rate of which is to be measured. Opposed upstream and downstream transducers project acoustic energy toward one another through the fluid, along a plurality of parallel paths. Electronic circuitry coupled to the transducers provides an indication of the fluid velocity component along these paths and the values are modified by predetermined weighting factors. The transducers are placed in the pipe such that the acoustic paths are positioned at certain distances with respect to a reference.

Track positioning system for magnetic transducer head

Abstract: Data is recorded on a magnetic recording disk with data transducers adjustably positioned relative to a data zone. First and second control tracks are interspersed with the data zone in a parallel relationship. Positioned over each control track is a position sensing transducer mechanically linked to the data transducers. The control transducers each comprise core gaps used both for prerecording and subsequent reading of a position control pattern along their respective tracks. The core gaps extend diagonally at a predetermined angle to the direction of movement of the medium and provide control patterns defining multiple transition groups, the number of transitions related to a corresponding number of data tracks to be read by the data transducers. Positioning of the position sensing transducers is accomplished by measuring the time relationship between the output pulses of the two control tracks and by relating the resulting time differential to the radial distance over which the control head is to be actuated.

Transducer structure and support for fluid measuring device

Abstract: Transducers are positioned on opposite sides of a fluid conduit and are longitudinally displaced from one another along the axis of the conduit. Each transducer contains a transmitting and receiving transducer element which produces output energy in a direction represented by a ray forming an angle to the axis of the flow conductor, such that the sine of the angle is equal to the ratio of the velocity of sound in the transducer body supporting the transducer crystal to the shear mode sound velocity in the conduit walls of the conduit conducting the fluid. The longitudinal spacing between the centers of the transducers on opposite sides of the conduit is such that it intercepts a sonic beam passing through the liquid. The sine of the angle of that beam passing through the fluid within the conduit and between the transducers makes with a line normal to the axis of the pipe, equals the ratio of the velocity of sound in the liquid to the pipe shear mode velocity of sound in the conduit. A novel mounting clamp and spacing strip is provided to automatically adjust the longitudinal spacing between the transducers and to ensure that the transducers can be securely clamped to the pipe without displacing the transducers during the clamp tightening process. The rear of the transduer crystals is covered with damping layers to damp out the trailing portions of the transmitted signal. The flow display computer associated with the transducers is arranged to count clock pulses during transmission upstream between the transducers and then during transmission downstream between the transducers. The difference in the number of pulses counted is then proportional to the velocity of the fluid within the conduit. The difference in pulse count may be previously compensated for by changes in the sonic beam angle due to possible changes in the liquid sound velocity so as to eliminate any dependence on sonic velocity in the resultant flow velocity computation.

System for providing an indication of wind shear

Abstract: The output of a transducer providing a signal in accordance with the instantaneous air speed of an aircraft is differentiated and fed to a summing device which subtracts therefrom a signal in accordance with the horizontal acceleration of the aircraft, this signal being derived from the output of an inertial instrument such as an accelerometer. The output of the summing device represents the magnitude of the wind shear condition (rate of change of wind velocity with changes in altitude). This signal is fed to appropriate indicator means which may comprise an appropriate display, a peak magnitude storage device, a warning device indicating a dangerous wind shear condition, or a telemetering device providing a wind shear reading to a ground station for use in advising other aircraft.

Acousto-optical data input transducer with optical data storage and process for operation thereof

Abstract: The present invention is directed to the improvements in an apparatus for holographically recording data on a storage medium with the data being block-organized holographic data by spatially modulating a laser beam into a plurality of object beams which are directed at a storage medium to interfere with a reference beam to form the holographic recording. The improvements are that the means for spatially modulating comprises an acousto-optical light deflector having a large area, piezoelectric sound transducers disposed on the one side thereof, the sound transducer having n electrodes spaced thereon to form n transducer units which receive a signal with a frequency mixture of m frequencies to deflect the beam passing through each unit into m beam directions with the light frequency of each beam having a Doppler shift associated with the amount of deflection. The apparatus also includes providing a lens raster consisting of n times m lens elements arranged in a manner to widen each of the object beams to illuminate the entire hologram and means for compensating for the Doppler shift in the light frequencies of the object beams.

Method and apparatus for ultrasonic material level measurement

Abstract: Ultrasonic pulses are transmitted from the top of a tank or bin by a transducer and reflected by the material contained therein and received by the same transducer. In the short range mode, two millisecond pulses at sixty second intervals provide a measurment of from two to twenty one feet. Failure to detect a reflected pulse in the short range mode automatically switches the device to the long range mode utilizing ten millisecond pulses at three hundred millisecond intervals. After a pulse is transmitted the energy received by the receiver is converted to a digital value each millisecond and compared to the highest previously converted digital value so that the time of the largest received reflection signal and consequently the distance to the material surface may be determined. The echo signals from eight successive long range pulses are digitized and then integrated according to apparent object distance so that the sum of the true echo signals returned from the material surface is substantially greater than the sum of random noise signals for each transmitted pulse. After each eight-pulse long-range sequence, apparatus electronics automatically return to the short-range measurement mode to start a subsequent measurement sequence.

Ultrasonic continuous wave particle monitor

Abstract: Apparatus for sensing particles in a fluid medium comprising an ultrasonic resonant cavity for containing a fluid medium. A first transducer on one side of the cavity continuously propagates thereacross ultrasonic compressional waves whose phase and amplitude are perturbed by the presence of particles in the fluid medium. A second transducer positioned on the opposite side of the cavity from the first transducer substantially parallel to and in registry therewith receives the ultrasonic waves and converts them to rf electric waves of the same frequency, the rf electric waves having their phases and amplitudes modulated in response to any perturbations in the ultrasonic waves. The rf waves are amplified and fedback to the first transducer thereby to establish an oscillatory circuit. An attenuator in the oscillatory circuit causes its operation to be marginally oscillatory whereby small changes in the amplitude of the rf waves caused by any perturbations in the ultrasonic waves produce relatively large changes in the amplitude thereof. A detector responsive to perturbations in the rf wave demodulates the amplified rf wave to produce signals indicative of the presence of particles in the fluid medium. Thus, enhanced sensitivity to small changes in the ultrasonic properties of the fluid medium caused by the presence of particles therein is achieved.

Ultrasonic generator drive circuit

Abstract: The ultrasonic generator comprises a transducer which is adapted to vibrate in a fundamental frequency mode and the harmonics thereof in response to a square wave signal which is applied thereto. The transducer is of the piezoelectric type which has a capacitor loading effect. A square wave generator is provided for generating a square voltage wave and driving means comprising high speed switching transistors is responsive to the signal from the square wave generator for driving the transducer with a square wave. The transistors are switchable between conducting and non-conducting states and are connected to the square wave generator so that the transistors are switched in phase opposition to each other. A non-resonant inductor connects the pair of transistors with the transducer to limit current flow and to permit application of the square wave to the transducer. An alternate embodiment utilizes a balancing transformer to eliminate the normal high common mode switching current.

Ultrasonic transducer mounting and coupling assembly

Abstract: An ultrasonic transducer apparatus for sensing flow velocity through a pipe wall has a pair of strap-on transducer assemblies for securing to an unprepared pipe surface, the energy coupling between each transducer unit and the pipe or other working device being provided by an elastomeric contact pad, which also facilitates rapid replacement of the transducer crystal, by simplified assembly.

Piezo-optic measuring transducer and accelerometer, pressure gauge, dynamometer, and thermometer based thereon

Abstract: A piezo-optic measuring transducer is disclosed herein and an accelerometer, a pressure gauge, a dynamometer, and a thermometer based thereon. The piezo-optic measuring transducer comprises two polarization-optical channels. Each of these channels includes the following components arranged in series downstream the luminous flux produced by a light source: a polarizer, an elastic element which is common to both channels and sensitive to stress variations therein caused by a variation in the measurand, an analyzer, and a photocell. Both channels are provided with a means for varying the intensity of the luminous flux incident upon one of the photocells which intensity variation is opposite in polarity to that in the luminous flux incident upon the other photocell. Both photocells are arranged in a differential relationship with the difference in the electrical signals produced thereby being representative of the measurand. An accelerometer, a pressure gauge, a dynamometer, and a thermometer can be provided on the basis of said transducer.

Apparatus for controlling vibrational chatter in a machine-tool utilizing an updated synthesis circuit

Abstract: A method and apparatus for controlling vibrational chatter in a machine tool operation wherein a workpiece and a tool are mounted in a manner to permit controlled and forced engagement of the tool and workpiece to remove material from said workpiece. A first transducer is spatially disposed from the tool-workpiece interface and generates an electrical signal representative of the applied cutting forces on the workpiece. This force signal is applied to a workpiece movement synthesis circuit for continuous calculation of the workpiece displacement in response to cutting forces and in accordance with continuously updated static and dynamic characteristics of the machine structure and the workpiece. Simultaneously, another transducer on the machine structure continuously provides a tool acceleration signal for use in deriving an electrical signal representing the actual displacement of the tool. The synthesis circuit output signal representing the calculated workpiece displacement is electronically compared with the signal representing the actual tool displacement, with vibrational chatter occurring whenever the two signals are not equal and offsetting. When the two signals are not equal, the differential therebetween is used to generate an error signal for controlling a compensatory force actuator mounted on the machine structure. The compensatory actuator provides forces of controlled magnitude and frequency to the machine structure to offset and eliminate the vibrational chatter.

Position locating using digital logic controlled by pulse propagation time intervals

Abstract: Apparatus for gauging location of a movable element in relation to an end of an elongated impulse wave energy propagative member employing a sensing transducer adjacent one end of the member to sense first the direct impulse and thereafter the indirect impulse that is reflected from the opposite end. Processing of the sensing transducer responses and sequentially programmed digital measurement of time intervals associated with the duration and time relationship of such responses according to logic equations affords the desired location indication with automatic compensation for ambiently caused variations in shock wave propagation velocity in the member on repeating cycles of operation and with measurement accuracy independent of undue precision requirements in location of the sensing transducer in relation to the adjacent end of the member.

Signal detector comprising field effect transistors

Abstract: A signal detector including a transducer element, an X-Y addressed array of field-effect transistor electrically coupled, e.g., capacitively or directly coupled, to the transducer element, and means for addressing the transistor X-Y array.

Ultrasonic velocity and thickness gage

Abstract: An apparatus and method for determining a velocity of propagation and the thickness of different substances such as pipe walls utilizes a transducer connected to an A-scan. This material is placed in a holder between the transducer and a reflecting surface, the holder containing a fluid having a known velocity of propagation. The transducer converts high voltage electrical pulses produced by a generator into ultrasonic vibrations and also converts echo signals received from the reflecting surface and the material back into electrical pulses. A display device connected to the transducer displays these pulses and their exact position on the display device is used to determine the velocity of propagation and the thickness of the material.

Inertial microphone system

Abstract: An inertial-reaction microphone transducer mounting supported on the wearer's head away from the mouth for transmitting speech to the exclusion of ambient. A compliant, radial array of elastomer supporting material presses the transducer gently to the head. The transducer and supporting array may be mounted in a cup covering one ear, or it may be mounted in a capsule having an acoustical labyrinth frequency-selective vent for the neutralization of noise.

Blood pressure monitor leveling device

Abstract: An elevation and leveling adjustment arrangement for accurately locating pressure-to-current transducers, used in monitoring blood pressure during and post surgery, at an appropriate reference point relative to the patient. The pressure-to-current transducers are mounted to a platform or base which also has provided thereon level indicating means and optical means. The optical means in combination with the level indicating means is arranged to indicate when the base is properly leveled and the pressure transducers are at the same elevation as the reference point marked on the patient. In the case where an optical sighting means is employed, the reference point is directly viewable thereby. The platform further includes leveling adjust means which adjustably couples the base to a telescoping elevation adjust means, the latter of which provides fine elevation adjustment of the platform.

Flexible force responsive transducer

Abstract: Apparatus for monitoring the respiration of a patient through utilization of a force responsive transducer, which ideally is a capacitor transducer constructed from alternate layers of conductive and nonconductive materials that are flexible such that when placed beneath a patient or a resilient patient support, such as a mattress, the distance between the plates of the transducer changes for the purpose of producing electrical responses that upon amplification energize indicator means, such as a visual alarm or an audible alarm. The transducer is responsive to the vertical, reciprocating forces and motions caused by respiration and along with the associated circuitry, is sufficiently sensitive to energize an alarm upon sensing a cessation of respiration.