Showing papers on "Transducer published in 1976"

Capacitive touch-activated transducer system including a plurality of oscillators

Abstract: A human touch on an etched copper electrode produces a capacitive change to vary the time constant of an RC network as a part of an oscillator. The variation in the capacitance of the sensor changes the time constant of the RC network which results in a change in frequency of the output signal of the oscillator. This change in frequency thus varies with the human touch to the copper electrode. To develop a directional indication of the touch position, four electrodes are arranged in opposed pairs along orthogonal axes. Each electrode is part of an RC network connected to an oscillator with each of the four oscillators identified with one of the four positions along the orthogonal axes. The output signal from each of the oscillators is transmitted to timing and control circuitry that generates four separate pulse trains, one pulse train identified with each of four positions along the orthogonal axis.

Superconducting tunable‐diaphragm transducer for sensitive acceleration measurements

Abstract: A very sensitive resonant superconducting accelerometer has been developed as a component of a cryogenic gravitational‐radiation detector. The device consists of a superconducting test mass and superconducting coils carrying a persistent current. The displacement of the test mass modulates the inductances of the coils and generates an ac magnetic field which is detected by a Josephson‐junction magnetometer. The restoring force provided by the magnetic field is used to tune the resonant frequency of the transducer. The expected sensitivity of the system is better than 10−12gE/Hz1/2 (gE=9.8 m/s2) when used to detect accelerations at frequencies lower than 50 Hz. The system has been thoroughly tested and is being used to detect small accelerations of a gravitational‐wave antenna caused by the Brownian motion and other external disturbances. When used as a resonant displacement sensor in a gravitational‐wave detector cooled to 3 mK, this transducer is capable of converting a displacement of 4×10−20 m at 1 kHz...

Ultrasonic imaging system

Abstract: The invention is utilized in an apparatus for imaging sections of a body by transmitting ultrasonic energy into the body and determining the characteristics of the ultrasonic energy reflected therefrom. Such an apparatus typically includes a timer for generating timing signals, an energizing/receiving device alternately operative in response to the timing signals, and a display/record device, synchronized by the timing signals, for displaying and/or receiving image-representative electronic signals from the energizing/receiving device. In accordance with the invention there is provided a portable scanning module, suitable for being hand held, which comprises fluid-tight enclosure having a scanning window formed of a flexible material. A transducer is provided for converting energy from the energizing/receiving device to periodic ultrasonic energy and for converting reflected ultrasonic energy to electrical signals, the transducer having a plurality of defined segments. A variable delay device is coupled between the segments of the transducer and the energizing/receiving device, the variable delay means being responsive to the timing signals to effect electronic focusing of signals coupled therethrough. A focusing lens is coupled to the transducer. A fluid, such as water, is contained in the enclosure in the volume between the focusing lens and the scanning window. A reflective scanner device is disposed in the fluid between the lens and the window, and driving means, synchronized with the timing signals, is provided for moving the scanner device in periodic fashion.

Absolute measurement of acoustic particle velocity

Abstract: A method for the absolute measurement of acoustic particle velocity is described. The technique uses the Doppler shift in frequency of laser light scattered from small particles suspended in the medium and vibrating with sensibly the same amplitude as the surrounding molecules. The measurement is made over a small volume at the intersection of two focused laser beams and since no transducer is required the sound field is not disturbed. Some typical data are presented illustrating its use over the range of particle velocities 0.5–50 mm sec−1 rms and it is shown that the results should be reliable at frequencies up to 50 kHz in air and higher frequencies in more dense media.Subject Classification: [43]85.22; [43]35.65.

Transducer having piezoelectric film arranged with alternating curvatures

Abstract: A transducer of the type converting between electrical and mechanical energy by means of the piezoelectric effect in a supported sheet of uniaxially oriented, electrically polarized thin high polymer film such as polyvinylidene fluoride, having surface electrodes thereon for connection to an electrical circuit. The transducer is characterized by an arrangement of the piezoelectric film into a series of elongate curved cylindrical segments of alternating sign of curvature, with the surface electrodes on the film being divided in selected locations between adjacent segments. A useful level of elastic stability is achieved without using a static pressure difference on the film, good electromechanical coupling is attained, and the individual transducer elements formed by the divided surface electrodes may be usefully interrelated electrically to substantially cancel even order harmonic distortion and enhance linearity of operation.

Zinc-oxide thin-film surface-wave transducers

Abstract: The piezoelectric film layer transducer represents the most efficient method for generating and detecting surface acoustic waves on nonpiezoelectric substrates. ZnO, which has a strong piezoelectric effect and can readily be sputtered as an oriented crystalline composite on a wide variety of substrates, is a natural choice as the piezoelectric film layer. This paper summarizes a body of knowledge which has been developed on the characteristics of transducer quality ZnO film layers, and focuses attention on those sputtering parameters and microstructural properties which characterize a superior surface-wave transducer film. Requisite sputtering conditions are high substrate temperatures (150-300°C), modest deposition rates (0.5-1.0 µm/h), low background vapor pressures (<5 µm Hg) and an ultraclean vacuum system. Transducer quality surface-wave films are characterized by their optical clarity, high density, smooth surface, small crystallite size, and well-oriented crystallite axes. Such ZnO films will play an important role in future surface acoustic wave device technology.

Ultrasound imaging system with improved scan conversion

Abstract: In an improved system for medical imaging employing a transducer for transmitting and detecting ultrasonic vibrations, a digital scan converter accepts echo signals detected by the transducer and transducer position signals identifying the point of origin of the signals in a scanning plane transversely oriented relative to the body of the patient under study. The amplitudes of the echoes detected are stored at memory locations associated with the points of origin of the echoes. Peak detection analysis is performed on large echoes emanating from higher impedance tissue interfaces within the scanning plane, while cumulation and normalization analysis is performed on small echoes emanating from low impedance tissue interfaces within the scanning plane. Sensitivity to otherwise unobtainable image details, signal to noise ratio, and freedom from distortions is maximized, yet the improved system may be used

Noninvasive, continuous intraocular pressure monitor

Abstract: A noninvasive, continuous monitoring device for measuring intraocular pressure without interference with vision or normal activity of the patient. A miniature, planar-faced pressure transducer is fixed in a protruding section of a compliant hydrogel ring which has been tooled to conform to the spherical surface of the sclera. The hydrogel ring is placed noninvasively under the eyelids within the conjunctival cul-de-sac, the transducer being located in the lower temperal quadrant. Applanation of the sclera against the planar surface of the transducer results as a consequence of pressure from the separated tissues. Intraocular pressure readings are based on the variations in resistance in the strain gage elements of the transducer caused by the applied stress to the transducer diaphragm. Data is transmitted through connecting wires to a telemetry unit which transmits the data to a receiver-transcriber console. The total system permits free, uninhibited movement by the patient during the monitoring process and provides a record of intraocular pressure as a function of time-of-day.

High frequency wall‐pressure fluctuations in turbulent boundary layers

Abstract: Directly comparable spectral measurements with piezoelectric and pinhole‐microphone transducers show pinhole measurements to be significantly in error. The increase in measured rms pressure with reduction of transducer size is not nearly as dramatic as previous work has suggested.

Ultrasonic humidifiers, atomizers and the like

Abstract: Devices are disclosed using ultrasonic vibratory energy for atomizing water, gasoline or other liquids, for use in humidifiers, carburetors, and the like. A humidifier or atomizer is disclosed comprising an ultrasonic transducer having a vibratory member, together with means for producing ultrasonic vibrations thereof, a liquid supply conduit for directing a liquid into contact with the vibratory member, and a collection receptacle disposed below the vibratory member for collecting the liquid when the ultrasonic transducer is not in operation. The ultrasonic transducer may comprise an elongated front end mass, an elongated tail mass, a pair of piezoelectric elements disposed between such masses, an electrode plate disposed between the piezoelectric elements, means for clamping such masses together, with the piezoelectric elements and the electrode plate therebetween, and a mounting member having an opening therein slidably receiving the piezoelectric elements and portions of such masses, the mounting member having an internal peripheral slot within such opening for slidably receiving the electrode plate. The opening and the slot having a sufficiently loose fit with the piezoelectric elements, the masses and the electrode plate to obviate any substantial damping of ultrasonic vibrations. The transducer may be driven by a circuit comprising a solid state amplifier having input and output connections, a driver transformer having a primary winding connected to such output connection and a secondary winding connected to the electrodes of the piezoelectric transducer, a feedback transformer having a secondary winding connected to such input connection of the amplifier, and a primary winding connected to such electrodes through a phase shifting circuit.

Positionable transducing mounting structure and driving system therefor

Abstract: In a system mounting a magnetic transducer on the end of a thin leaf for sweeping motion displacement laterally to a track on a record surface, the present invention utilizes elements arranged as reversely deflectable leaf portions so as to maintain the transducer in substantially undeviating (normal) orientation with respect to the record surface. In one embodiment, the cantilevered leaf is composed of inner and outer (inboard and outboard) piezoelectric ("bimorph") bender elements having opposite polarizations and being cross-wired to produce the reverse deflections desired. The electrodes of the elements may also be divided longitudinally and coupled to bias voltage sources to provide controlled correction of azimuth error.

Hall effect displacement transducer using a bar magnet parallel to the plane of the Hall device

Abstract: A position indicating device for providing a generally linear output in response to displacement; the system includes a Hall effect device and apparatus for providing a response therein in accordance to displacement of a movable stylus or plunger and the method of making the same.

Sound reproduction system and device

Abstract: A sound frequency reproduction system and apparatus has a chair for a human. A transducer is vibrated by a sound signal of appropriate frequency. The vibrating shaft of the transducer is directly fitted to the framework of the chair. The sound signal is provided to an acoustic device, including a speaker, located near the chair.

Theory and numerical calculation of the acoustic field produced in metal by an electromagnetic ultrasonic transducer

Abstract: The equations for calculating the acoustic field produced within a nonmagnetic metal by an interaction of eddy current with a static magnetic field were obtained on the assumptions that (1) an ultrasonic wave is generated by the electromagnetic force through classical and macroscopic phenomena; (2) the electric, magnetic, and elastic properties of the metal are linear, isotropic, and homogeneous throughout the metal, which occupies semi‐infinite space; (3) the whole system is axially symmetric; and (4) eddy currents and elastic waves show a steady‐state sinusoidal variation. The acoustic field produced by a specific electromagnetic ultrasonic transducer with axial symmetry was calculated numerically, and the results showed a well‐defined ultrasonic wave beam, which was narrower than had been expected from the size of the transducer.Subject Classification: [43]35.60; [43]85.48.

Ultrasonic electronic lens with reduced delay range

Abstract: Ultrasonic reflections are received by a transducer array whose resultant signals are passed through an array of time-varying delay lines to provide focusing at all depths. The delay lines are made up of a combination of two components, one increasing and one decreasing with the distance to the axis of the array. This combination minimizes the range of delay variations required over the depth range. When using charge coupled devices as delay elements, this combination minimizes the required range of clock frequencies.

Observation of Transverse Zero Sound in Normal He 3

Abstract: The direct transmission of transverse zero sound between two $\mathrm{AC}$-cut quartz transducers is observed in the vicinity of 3 mK; at higher temperatures the transition to classical viscous shear-wave behavior is observed through the effect on the damping of a single transducer.

Crossed beam ultrasonic flowmeter

Abstract: A crossed beam ultrasonic flowmeter particularly suited for measuring two dimensional arterial blood flow has two pairs of ultrasonic beam transmitting transducers the beams of which are focused to intersect at a predetermined region through which dynamic particles undergoing velocity analysis are moving. The transducers are preferably coplanar and disposed equiangularly about an axis with the predetermined region located therealong. A receiver is disposed adjacent the axis intermediate the beams for receiving the Doppler shifted scattered signal. Following squaring of the scattered signal, bandpass filters separate the spectrally separated scattered signals resulting from the two pairs of transducers which then undergo spectral analysis to determine the necessary frequency and velocity information. One of the four transducers may be utilized as a second receiver to determine the third velocity component with a filter separating the scattered signal resulting from the transducer disposed diametrically across the axis. Alternatively, a fifth transmitting transducer and second receiver are disposed on opposite sides of the axis with a filter separating the scattered signal resulting from the fifth transducer. A pair of perpendicular linear B-mode scanning transducer arrays intersect at and extend perpendicularly to the axis for obtaining sagittal and transverse B-mode images of a conduit carrying particles undergoing velocity analysis.

Ultrasonic beam scanning

Abstract: Apparatus for the ultrasonic examination of an object comprises: A linear transducer array for directing pulses of ultrasonic energy along a plurality of beams into the object and receiving echoes of the pulses reflected along the beams by acoustic impedance discontinuities within the object, the transducer array comprising a plurality of adjacent transducer elements; and either Means for sequentially activating different groups of adjacent transducer elements within the array to direct a pulse of ultrasonic energy along a beam into the object and receive echoes reflected along the beam in each of a plurality of angular directions in a single plane; or Means for activating different groups of adjacent transducer elements within the array in turn so that each group directs pulses of ultrasonic energy into the object and receives echoes reflected along beams in a plurality of angular directions in a single plane.

CW ultrasonic bolt tensioning monitor

Abstract: This invention is a CW ultrasonic device for measuring frequency shifts of the peak of a mechanical resonance in a body. One application of the device is measuring the strain in a bolt. It also has other applications such, for example, as measuring the thickness of a body, measuring the depth of a flaw in a body, measuring the elongation of body and measuring changes in velocity of sound in a body. The body is connected, by means of a CW transducer, to electrical circuit means including a narrow band RF amplifier to form a closed loop feedback marginal oscillator that frequency locks the device to the peak of a mechanical resonance in the body. Thereafter, when the frequency of this peak changes, because of a physical change in the body, the frequency of the oscillator changes. The device includes an automatic frequency resonant peak tracker that produces a voltage that is related to a change in frequency of the oscillator. This voltage is applied to the RF amplifier to change the center of its frequency band to include the frequency of the peak and is a measure of the frequency shift. The device also includes a special transducer which requires contact to only one side of the body and provides high electrical isolation between its parts.

Curved polymeric piezoelectric electro-acoustic transducer

Abstract: An electro-acoustic transducer with a piezoelectric diaphragm supported by a support member having a curved portion for imparting a suitable resiliency and/or tension to said diaphragm to improve acoustic characteristics without reducing efficiency of the electro-mechanical conversion effected by the transducer.

Bragg coupling efficiency for guided acoustooptic interaction in GaAs

Abstract: The guided acoustooptical interaction on the (100) plane of GaAs is investigated as a function of waveguide thickness type of mode, acoustic frequency, direction of acoustic wave propagation, and substrate refractive index Our calculated results indicate that best efficiency is obtained for TE0 → TE0 optical modes and for acoustic surface wave propagating along the 〈011〉 direction at a waveguide thickness close to cutoff Under these conditions, approximately 75 mW of acoustic power is required for 100% diffraction. For a transducer aperture giving 50 Ω of radiation resistance, the rf bandwidth of the diffraction is limited essentially by the frequency bandwidth of the interdigital transducer. A comparison of the calculated results with experimental data at 1.06-μm optical wavelength is also given.

Radio-frequency tuned-circuit microdisplacement transducer

Abstract: An inductance-capacitance loop defines a resonant circuit and is arranged in a member subject to stress. Strains resulting from the stress vary the inductance or capacitance of the circuit, and its resonant frequency. A dip meter is used to detect the resonant frequency and thus provides a reading indicative of the stress in the member.

System and a method for equalizing an audio sound transducer system

Abstract: A system and a method of electronically equalizing the composite transfer function of a sound system and a room which receives the sound generated by the sound system. A test signal, such as white or pink noise, is applied to the sound system and a microphone for receiving the reference sound is placed in the room and has its output applied to an equalizer which comprises a plurality of contiguous narrow band filters covering the entire audio band. Each output signal from the filters is applied through an adjustable amplitude control means to a detector and each detected output signal is compared with a reference signal, such as the detected output signal from a selected mid-range filter and has its amplitude adjusted to provide a desired relationship with respect to the reference signal. After adjustment of the equalizer, the test signal and the microphone are disconnected from the system and the sound signal source is applied through the equalizer to the loudspeaker system.

Vacuum stressed polymer film piezoelectric transducer

Abstract: An electro-acoustic transducer has a piezo-electric film polymer diaphragm which is stressed to a part spherical surface and the periphery of which is clamped. Electrodes placed over the surface of the diaphragm apply an electric field transverse the plane thereof which causes elongation parallel to the plane of the diaphragm. The rim of the diaphragm is mounted in a supporting framework which forms part of an enclosure isolating one side of the diaphragm from the atmosphere. The enclosure may be evacuated to improve the performance of the transducer by avoiding problems due to the formation of standing waves within the enclosure.

Interference canceling method and apparatus

Abstract: Apparatus for canceling interference suitable for use in conjunction with stationary phased array antennas or transducer arrays designed for satellite or other communication systems employing N-phase PSK (Phase Shift Keying) modulation is disclosed. The techniques used in the apparatus involves processing of signals received by a main array and an auxiliary array of a phased array antenna so that an error signal is derived which is fed back to circuitry which modifies at least one signal received by the auxiliary array. The modified signal or signals are summed with the signal received by the main array so that a sum wave is generated whose interference component is minimal. The feedback circuitry exponentiates or raises the sum wave to the N th power to eliminate modulation, since the N th power of an N-phase PSK signal is a narrowband carrier. Then a term proportional to the desired signal raised to the N th power is filtered from the exponentiated sum wave and the remainder is utilized for error signal purposes. This technique operates without sacrificing bandwidth or degrading the desired signal and permits reception of signals with frequency spectra substantially overlapping one another.

Load measurement device

Abstract: Apparatus for sensing and measuring the torque output of a rotary device such as a gear reduction box by inserting an especially machined or configured adaptor between the shaft bearing and the bearing mounting housing. This adaptor transducer will have strain gages mounted on it in spaced relationship so that the tangential force from the gears reacting on a shaft will produce a deflection in the adaptor transducer which will be detected by the strain gages. The strain gage signal then will be sensed, amplified and can be recorded on an analog read out type meter or monitored continuously on a pen-type recorder or other conventional instruments. The strain gages can be calibrated so the output of the recorder will convert the signal into a direct reading of the torque output transmitted through the gear reduction box.

Process and apparatus for controlling engine operation near the lean-running limit

Abstract: The fuel supply control pulses of an internal combustion engine may be shortened or lengthened to provide operation of the engine at a definite fuel-air ratio. When operation takes place in a leaned-out region, the engine suffers dynamic instability, resulting in rapid fluctuations of the rotational crankshaft velocity, superimposed on regular, periodic changes due to compression changes. The maximum and minimum crankshaft speeds are measured at two different locations of the angular path by passing markers in front of an inductive transducer. The output signals from this transducer are fed to a gating circuit which controls the counting modes of a digital counter which is also supplied with a clocking pulse train at a constant, high frequency. The gating circuit causes alternate upward and downward counting in the counter so that a net difference of counted pulses is formed after each two successive counting periods. This difference is stored until a particular piston of the engine has returned to the functional position it occupied during the first measurement. The measurement is repeated and the difference between the two measurements is compared. The result of this comparison forms a measure of engine roughness and is used for fuel control.

Force measuring apparatus

Abstract: A novel flexure-based transducer is capable of measuring forces along a first axis and moments about a second axis perpendicular to the first axis, using strain-gaged cantilever beams. The configuration facilitates scaling for selected sensitivity to particular inputs. A second embodiment permits the strain gages to be completely sealed from the environment. Also disclosed is a platform weighing system of the force transferral type using four of the novel flexure members with only a single load cell, and permitting the relative sensitivity of each flexure member to be readily adjusted to provide equal sensitivity irrespective of the location of the applied load on the platform.

Control circuit for an ultrasonic dental scaler

Abstract: A control circuit for an ultrasonic dental scaler, comprising a transducer driven by a frequency-controlled oscillator, is disclosed. The control circuit is operable for continuously regulating the oscillator frequency at substantially the same value as the resonant frequency of the transducer with a dental tool attached to it and for controlling the mechanical power output of the transducer. The transducer can be drivingly connected to a work tool for transmitting mechanical energy thereto. The regulation of the oscillator frequency is accomplished by simultaneously applied control signals derived from the current passing through the transducer and from the voltage across the transducer, to compensate for supply voltage variations. Moreover, the mechanical power output of the transducer is controlled such that it is reduced whenever the contact pressure of the work tool exceeds a predetermined maximum value. Such excessive pressure is monitored as the amplitude or phase variation of the voltage or of the current of the transducer.

Transducer assembly vibration sensor

Abstract: A sensor for sensing vibrations in a transducer assembly and for generating an electrical signal indicative of the vibrations is disclosed. The sensor includes a piezoelectric generator which is mounted with a bimorph on a common substrate. The piezoelectric generator and bimorph have a common cantilevered end portion and an opposed deflectable free end portion so that deflection of the free end portion of the bimorph causes a corresponding deflection of the free end portion of the piezoelectric generator, whereby the piezoelectric generator generates an electrical indication of the instantaneous degree of deflection of the bimorph.