Abstract: Weight sensing apparatus, typically a personal scale, employs a thin film of piezoelectric polymeric material as the transducing component for converting mechanical pressure in the form of applied weight to voltages which are digitally displayed in pounds.

Abstract: An engine having a combustion driven piston is provided with piezoelectric transducer means responsive to piston movement to generate a voltage.

Abstract: The level detector is to be used for starting and stopping an electric system such as a pump. It comprises a piezo-electric crystal (31) squeezingly mounted between two elastically resilient membranes (22, 23) situated between two squeezing members (11, 12). These squeezing members form a top part (11) and a bottom part (12), respectively, which together form a sensor housing (10). On the outside the membranes are coated with a thin, insulating plastic layer (21, 24) and form the electric connection to the crystal. The two membranes are kept separated by means of a plurality of insulating, annular disks (25-28). In this manner a sturdy and reliable mounting of the piezo-electric crystal is obtained.

Abstract: A pressure sensor having a semiconductor body is disclosed. The sensor comprises a substrate of a compound semiconductor and an epitaxial layer of a mixed crystal, in which different conduction band minima with different effective masses are closely adjacent energywise, particularly from the mixed crystal series gallium-aluminum-arsenic with the composition Ga.sub.1-x Al.sub.x As, in which the aluminum concentration is 0.19.ltoreq.x.ltoreq.0.43. The sensor described has a simplified design and predetermined pressure ranges can be set by varying the concentration of the crystal constituents.

Abstract: A piezoelectric element for incorporation in pressure, force or acceleration transducers, in which at least two piezoelectric flat plates loaded in shear mode are arranged on both sides of a central support and are retained under compressive pre-tension by pressure distribution members bearing externally on the piezoelectric plates; a compression form member provided with a location hole for the support, the piezoelectric plates and the pressure distribution members is fitted over the pressure distribution members by direct or indirect shrinking the pressure distribution members are preferably made of two exact fitting cylindrical segments transmitting the tension forces evenly over the piezoelectric plates.

Abstract: A sensor structure for attachment to the foot of an animal to continuously measure the pressure of the foot against a reactive surface. The sensor structure provides a small flat particularly configured piece of piezoelectric plastic, encapsulated to protect it and interconnected electrically with telemetry and analyzing apparatus. Plural sensors may be used in various parts of a foot to determine local pressures. The sensed pressure may be recorded and annunciated by various known means to aid analysis of foot and limb activity and general animal physiology.

Abstract: Apparatus for measuring or otherwise checking phase angles between different lines of a multi-line fuel injection pump for an internal combustion engine, comprising an injector block defining a plurality of cavities. These cavities receive the nozzle ends of the fuel injectors of the different lines. Pressure sensors are arranged in communication with the cavity interiors to detect changes in pressure therein, and means are connected to the pressure sensors to provide a measurement of, or other check on, the phase angles of the different lines.

Abstract: A pressure-sensitive transducer arrangement comprises a matrix of transducer elements which are formed at the points of intersection of row conductors (35, 36) and column conductors (5 to 7). A flat substrate (2) is provided with column conductors (5 to 7), each of which is covered with a similarly-structured piezoceramic material as a dielectric medium (15 to 17). This piezoceramic material is separated from the row electrode (35, 36) by empty spaces (24 to 26). Due to bilateral spacing of less than 100 micrometers for the row conductors and column conductors, a sensor matrix is produced with a dense packing of pressure-sensors functioning as capacitors which are formed at the cross-points of the row and column conductors. These sensors are particularly adapted for use in the gripping device of an industrial robot and make it possible to detect and determine the position of robot workpieces.

Abstract: An electromechanical transducer for the generation of an electric signal in response to a force or motion applied to the tactile surface thereof. The electromechanical transducer comprises a stack of planar sheets of a piezoelectric polymer material, each sheet having two opposed broad flat faces and at least one tactile surface at one longitudinal end, separate electrodes covering portions of each flat face of the sheets in predetermined patterns, terminals electrically connected to said electrodes for passage of said electric signal and means for detecting and amplifying the electric signal generated in response to a force or motion applied to the tactile surface of the transducer.

Abstract: A force and pressure transducer comprises a plate-like crystal. Two separate portions of the crystal are maintained in oscillation at separate frequencies by a circuit. The force to be measured, is applied by a seating to a part of the crystal edge such that compression in one of the oscillating portions causes the frequency of that oscillating portion to change substantially whereas the frequency of the other portion changes only minimally.In the past it has been difficult to manufacture crystals in which the frequency versus temperature response of each of the two oscillating portions was sufficiently well matched to permit the difference frequency between the portions to be used as the instrument output signal.This invention resides in the application of a second fixed force by a spring via a seating to a second part of the crystal edge in such a way as to influence the frequency of oscillation of this second portion.

Abstract: A combustion pressure peak detector comprised of a pair of flat annular piezo-electric elements separated by a flat metal electrode plate are located on a bolt for securing a cylinder head to a block of an internal combustion engine. The piezo-electric elements are engaged on opposite sides by two pressure plates adapted to engage the head of the bolt and the cylinder head respectively. At least one of the pressure plates may have a cup-shaped configuration for enclosing the piezo-electric unit and an inter-fitting projection and notch arrangement may be provided on the respective pressure plates to prevent relative rotation between the two pressure plates during tightening of the bolt.

Abstract: A force sensor comprising a field effect transistor (FET) structure formed on a substrate, having an insulating layer overlying the substrate adjacent to the channel region of the transistor structure. A layer of piezoelectric material overlies the insulating layer, the layer of piezoelectric material having a portion which extends beyond the insulating layer to form a cantilever structure overhanging a portion of the channel region. A control electrode overlies the cantilever structure. Forces acting on the cantilever structure modify the charge distribution in the underlaying channel region, thereby to cause the drain current of the transistor to vary with any variation of force on the cantilever structure.

Abstract: A quartz crystal vibrating diaphragm pressure sensor includes a primary quartz crystal body having a diaphragm formed therein and electrodes on each side of the diaphragm for piezoelectrically exciting thickness shear mode oscillations of said diaphragm, said oscillations varying in frequency in accordance with variations in fluid pressures applied to the surfaces of said diaphragm. A second identical or substantially identical diaphragm similarly excited but exposed to a constant pressure provides a reference frequency for providing precision difference frequency pressure measurement and for inherently compensating for ambient conditions affecting both diaphragms.

Abstract: An ultrasonic detector is provided wherein electrodes are formed on the front and rear surfaces of a high polymer piezoelectric film, such that opposing electrode portion and nonopposing electrode portions are alternately and continually formed, most parts of the electrodes on the front and rear surfaces being opposed to each other through the piezoelectric film at the opposing electrode portions, most parts of the electrodes on the front and rear surfaces of the film which are different from the most parts of the electrodes at the opposing electrode portions being shifted from each other at the nonopposing electrode portions so as to have substantially no capacitance, and the piezoelectric film is wound around a base in an even number of layers such that the opposing electrode portions overlap each other and the nonopposing electrode portions overlap each other.

Abstract: A knock detecting apparatus for detecting the occurrence of knocking in an internal combustion engine by detecting variations in the pressure of engine cooling water. A sealed double diaphragm structure is formed by a first diaphragm which is directly responsive to variations in the cooling water pressure and not resonant at the knock frequencies and a second diaphragm which is resonant at the knock frequencies. A noncompressible fluid is contained in the sealed double diaphragm structure between the two diaphragms. Pulsations of the second diaphragm, resonant at the knock frequencies, are detected by a magnetic device or a piezoelectric device operative to output an ac signal.

Abstract: A piezoelectric device, comprising a number of polarizable ceramic plates 1 which are stacked with intermediate metal plates which serve as electrodes. The stack is subjected to a large amount of preload by a preloading element having a relatively flat spring-force characteristic over the piezoelectric operating range of the device which is formed by a cylindrical housing having two sets of parallel pairs of slots 7, 10, rotationally displaced by 90 degrees, the preloading force being applied to the stack by threaded end plugs 4 and 5. The ceramic plates are polarized only after assembly and preloading.

Abstract: A device is disclosed which is useful to generate electric signals particularly in close quarters. The preferred embodiment is described in terms of a piezoelectric signal generator incorporated into the beltline trim of an automobile and an alternate configuration in a flat sheet metal application. The invention is discussed in terms of its ability to take advantage of already existing structural elements of its host body and its ability to be attached without putting holes in such structure.

Abstract: A single beam force transducer is provided with integrally affixed isolation springs which are axially compliant and unbalanced in their spring rates so as to induce beam bending due to applied tension and compression. The amount of bending introduced due to applied tension will be of a precise magnitude so as to substantially cancel undesirable non-linear vibration effects.

Abstract: A single beam force transducer has a beam characterized by a thickened central portion and tapered outward portions. The support members of the transducer are thickened and are thus stiffer while the isolator masses are shortened. These critical configuration changes raise the undesirable "tuning fork" resonant frequency of the beam supporting structure far above that of the beam and ensures that the isolating structure behaves as a rigid body.

Abstract: A variable pressure piezo electric generator comprised of a furnace chamber, a refrigerant chamber surrounding the furnace chamber in heat exchange relation thereto and a condensing chamber in communication with the refrigerant chamber. The refrigerant chamber contains a liquid refrigerant that is vaporized by the furnace heat and flows into and through the condensing chamber where it condenses. Piezo electric elements are mounted in the condensing chamber in the path of the pressurized refrigerant. An apertured plate is mounted in the condensing chamber between adjacent pairs of the piezo electric elements. The apertures in the respective plates vary in size which causes refrigerant pressure variations. As a result, the refrigerant exerts mechanical forces on the piezo electric elements causing them to produce electricity.

Abstract: In addition to having at least one piezoelectric sensor element, a transducer is provided with at least one further measuring element, which is influenced by the state variable to be measured in the same way as the piezoelectric sensor element, and has its own signal lead.The additional measuring element may also be a piezoelectric element which may be excited so as to produce mechanical vibrations by utilizing the inverse piezo-effect, the change of the vibration characteristics of the vibration system consisting of the excited piezo-element and its environment serving as a measurement value for a static or quasi-static measurement.

Abstract: A force or fluid pressure transducer comprises two plate-like crystals. The force is applied to the first of the two crystals in a direction generally along the crystal faces by two seatings situated at opposing edges of the crystal.An oscillating portion of this first crystal changes its frequency by an amount which is a very accurate measure of the force, providing the ambient temperature of the instrument remains constant.The present invention resides in a second crystal secured to the first crystal at particular force insensitive points, there being very small spacing between the two crystals. The second crystal sustains a negligibly small amount of the force and hence a similar oscillating portion of this second crystal undergoes negligibly small frequency change.Means are provided for adjusting the steady-state temperature behavior of one crystal with respect to that of the other in order to remove residual errors.

Abstract: A fuel injection arrangement for an internal combustion engine, has a control device for receiving an electrical signal corresponding to a quantity of applied fuel, comparing an actual value with a nominal value of the supplied fuel quantity, and producing a correcting signal for fuel supply, and also has a measuring element for measuring the quantity of the supplied fuel and producing the responding electrical signal, wherein the measuring element includes a quartz pressure measuring diaphragm producing the electrical signal by a piezoelectric effect on quartz because of a differential pressure on the measuring diaphragm.

Abstract: An injection timing transducer is provided for use with the fuel delivery system of a compression ignition engine. The transducer is operatively associated with the fuel flow path and provides a signal indicative of fuel pressure pulsations within the fuel delivery system. The electrical signals are representative of the derivative or rate of change of fuel pressure as a function of time and are thereby particularly suited for indicating the onset of fuel injection to the engine. The transducer includes a housing member connectable in the fuel flow path intermediate a fuel pump and injector for defining a chamber through which the fuel may pass and for providing a sensor mounting surface external to the chamber but in pressure transmitting relationship with the fluid path. A piezoelectric sensing element is affixed to the sensor mount surface of the transducer housing member.

Abstract: Electrical connections to thin film coatings, especially useful in a fluid flowmeter, have a conductive coating pressed against a rigid, relatively long, connector bar by conductively coated pads of elastomeric material at a selected controlled pressure, with the electrical connections to the film coating being made through the bar and pads. Utilizing this method, localized high stress areas which cause damage to the thin film are avoided, and low current densities are accomplished by the controlled contact pressure over a large area of the film coating.

Abstract: A stress compensated thickness-shear resonator is of an orientation (yxwl) .phi./.theta. selected from loci of stress compensated orientations provided for both the fast and slow thickness-shear modes of vibration. A stress compensated orientation is used in an oscillator for stable frequency-stress behavior. A stress compensated orientation having large-valued temperature coefficients of frequency is used in a temperature sensor for precision measurements. A stress and temperature compensated orientation is used in a pressure sensor such that the temperature compensated thickness-shear mode is used for pressure measurement while the stress compensated thickness-shear mode is used to compensate for effects of temperature.

Abstract: A transducer with a flexible sensor element for measurement of mechanical values, at least one flexible piezoelectric sensor element being provided for piezoelectrical or capacitive measurement, the opposite surfaces of the sensor element being at least partially connected to electrically leading contact surfaces.

Abstract: A pressure transducer is provided with a housing in which is mounted a pressure sensitive piezoelectric crystal for converting pressure changes of a rapidly moving gas to electrical signals. The crystal is mounted within the housing in a floating manner by a brass damping bar which damps extraneous acoustic oscillations. The hollow interior of the housing is filled with beeswax that surrounds the damping bar and the piezoelectric crystal, so that any parasitic oscillations arising from housing wall are damped.

Abstract: A mounting structure for crystal resonators used as frequency standards and transducers which maximizes performance and reduces the sensitivity to environmental errors. In one embodiment, force sensitive crystal resonators having inherent unmounted temperature sensitivities are used in conjunction with reactive spring-like mounting arrangements having predetermined temperature stress characteristics such that the thermally induced mechanical stress of the mounting arrangements changes, compensates, and optimizes the overall combined temperature characteristics. In another embodiment crystal resonators are isolated from the external environment so that they are capable of sensing forces while operating in a vacuum or inert atmosphere. Environmental isolation is provided by bellows and/or diaphragm arrangements used alone or in conjunction with air-tight enclosures which enable forces to be applied to stress-sensitive crystals while isolating the crystals from the external force producing environment.

Abstract: A transducer device for measuring mechanical values on hollow bodies, which comprises a housing and at least one elastic sensor element mounted in the housing. The element is so formed as to be connected with at least two points of the housing and has a free length between these connecting points so as to be stretched over the surface of the hollow body when the transducer device is attached.

Abstract: A broadly tuned self resonant knock sensor includes a piezoelectric element mounted on a central mounting stud. The element includes a generally annular vibratable portion having a variable radial dimension so as to exhibit resonant vibrations at a plurality of relatively closely spaced resonant frequencies essentially spanning an engine determined knock frequency band. In its preferred embodiment the element comprises a circular plate having piezoelectric generating means and an axis offset from the axis of the mounting stud.

Abstract: Disclosed is a method and means to increase or decrease, on demand, the drag exerted by a fluid on a boundary. The boundary comprises a surface portion of a structure enclosing a moving fluid or may comprise a portion of the outer surface of an object moving through the fluid. Drag is varied by means of a set of piezoelectric sensors and an accompanying set of piezoelectric driver elements arranged in close proximity to one another at the boundary and electrically interconnected so that the pressure exerted by the moving fluid is sensed by one or more sensors and converted to an electrical signal which is then transformed into an electrical drive signal which is applied to one or more driver elements to cause a flexing of the driver element(s) in a predetermined direction so that drag is either reduced by moving the driver(s) away from the fluid or increased by moving the driver(s) towards the fluid.

Abstract: There is disclosed a rectangular diaphragm employing a quasi rectangular active area. The diaphragm as configured has an aspect ratio which is the length to width ratio of greater than 3:1. The active area of the diaphragm, which is the area which most readily deflects upon application of a force to the diaphragm, is formed by an anisotropic etching technique to provide steep vertical sidewalls. The diaphragm structure thus described exhibits as a response to an applied force or pressure, a maximum longitudinal stress and a minimum transverse stress and can accommodate piezoresistive elements located within the active area of the diaphragm.

Abstract: An intrusion sensing line to be buried or emersed in a medium and operative to deliver electrical signals in response to pressure changes as the medium is stressed, the line including multiple metal shells each having a transducer bonded to a flexible diaphragm surface inside the shell, and the shells being spaced apart and joined by soft metal tubing, the tubing and shells being metal-to-metal bonded at all joints and sealed to retain a dry inert gas, and the transducers being insulated from the shells to which they are bonded and wired together, preferably with alternating polarities, by insulated wiring extending through the tubing and the shells.

Abstract: A piezoelectric crystal element for use in force and pressure transducers and accelerometers, consisting of a monocrystalline cubic-polar material with electrode faces that intersect one of the crystallographic principal axes X,Y,Z at an angle .alpha.'=arc sin .sqroot.p and the other principal axes at .beta.'=.+-.1/2 arc cos p, wherein p=0 for the piezoelectric orthoaxial shear effect, p=1/3 for the longitudinal piezoeffect and p=1 for the transverse piezoeffect.

Abstract: A piezoelectric element is arranged to receive a mechanical pressure signal and to generate a resultant voltage which is connected to a voltage threshold device for detecting a voltage signal above a predetermined threshold value. The threshold device comprises a two state circuit operable to change state in response to a signal above the voltage threshold. The apparatus is especially adapted to be incorporated within a platform scale for energizing a scale reading indicating system.

Abstract: A system for isolating the mounting pads of a vibrating beam or tuning fork force transducers from longitudinal vibrations generated by transverse vibrations of the beam or tuning fork tines which extend between the mounting pads. The system includes an arrangement of longitudinally resilient support links and masses that flex responsive to change in the length of the beam or tines as the beam or tines vibrate transversely. The support links and masses thus isolate the mounting pads from the longitudinally vibrations of the beam or tuning fork tines while allowing transmission of forces applied between the mounting pads which vary the force dependent resonant frequency of the beam or tuning fork.

Abstract: An apparatus for detecting a residual quantity of toner remaining in the supply hopper of a copying machine includes a piezoelectric vibrating element disposed in a wall of the hopper and having a surface normally positioned in contact with toner in the hopper, and an electronic circuit for causing vibration of the element at a predetermined frequency and for detecting changes in operating characteristics of the element as representative of a decrease in the amount of toner in the hopper to operate a warning device.

Abstract: A transducer for sensing and monitoring the injection of fuel into a fuel injection type engine including a transducer comprising a flexible collar of low mass and a flexible piezoelectric element mounted on the fuel line to sense the change in the circumferential dimension of the line due to the surge of pressure created in the line as the fuel is injected through the line into the engine.

Abstract: An input device for a computer controlled visual display enables an operator to instruct the shift of a display element in a chosen direction by hand movement of the input device sensor in an analogous direction over a plane surface. The sensor includes a conventional piezoelectric audio pick-up which produces a succession of unidirectional pulses when the stylus is drawn across a microscopically textured surface such as a sheet of paper, the polarity of the pulses being indicative of the direction of motion along a selected axis. A second pick-up is arranged to give a maximum response to motion along an orthogonal axis and for the component of motion on each axis a bi-directional pulse counter enables the direction of motion to be determined by a comparison of the counts held in successive time intervals.

Abstract: An air gun firing sensor apparatus and system are provided for determining the instant of firing of an air gun by sensing pressure changes within the air gun when it is being fired. A pressure-change-sensitive transducer assembly is inserted into a socket in the housing of a solenoid-controlled valve of an air gun with a passage from the air gun communicating with the transducer for transmitting to the transducer a pressure surge occurring within the air gun whenever it is fired. The transducer assembly has a cylindrical casing with a head mounted at one end. The head includes a plurality of spaced recesses which are adapted to communicate with the passage leading from the air gun.

Abstract: A vortex-shedding flowmeter in which a liquid or gas to be metered is conducted through a flow tube having a shedding body transversely supported thereon. Torsionally-supported at a downstream position behind the shedder on a shaft which projects outside of the flow tube to provide a shaft extension is a sensor, the pivot axis of the shaft being normal to the longitudinal axis of the tube. In operation, as the incoming fluid stream is divided by and flows past the shedder, vortices are successively detached therefrom and appear alternately on either side of the sensor, thereby developing a torque about the pivot axis. The torques are developed alternately in the clockwise and counterclockwise directions, causing the torsionally-supported sensor to oscillate at a rate proportional to the flow rate of the fluid. These oscillations are converted by a transducer operatively coupled to the sensor into a corresponding electrical signal.

Abstract: A force detector for detecting a force directly as a stress is disclosed which includes a piezoelectric unit for detecting a stress, a vessel for housing the piezoelectric unit, and a seal member for sealing the piezoelectric unit firmly and integrally in the vessel.

Abstract: A piezoelectric knock sensor comprises a flexing plate at one end of a generally cylindrical case with a mounting stud extending perpendicularly therefrom and a piezoelectric element attached to the flexing plate within the case for flexure with the flexing plate. When the sensor is attached to a component of a multicylinder, internal combustion engine, the case vibrates interactively with at least a portion of the component through the flexing plate and exhibits both an interactive resonance with the component for a wide resonance peak and response to transverse as well as axial vibrations. The sensor is thus capable of resonant response to knock-induced vibrations from all the cylinders even if the characteristic knock frequencies of the individual cylinders differ over a range too great to be encompassed by a self-resonant sensor. In addition, the sensor has the comparatively high output level of a piezoelectric device and simple construction suitable for mass production.

Abstract: A postage scale includes a directly loaded weight-to-period transducer which provides an oscillating output, the period of which varies as a function of the weight to be measured. The transducer includes a disc of piezoelectrically active material bonded to an inactive substrate base which dishes at its center in response to the weight to be measured. The transducer frequency output is processed to provide a digital period signal. A reference oscillator having matched temperature characteristics generates a high frequency count calibrated for scaling the transducer period to a weight count. The high frequency signal and the period signal are gated to provide an input to a counter which generates a digital weight information signal. The weight information signal is transmitted to a mailing system processor for use in determining the postage requisite for mailing the article.

Abstract: A transducer and associated diagnostic system for fuel injected diesel engines of the type having glow plugs to provide supplementary ignition during starting and warm-up periods. A piezoelectric transducer unit is adapted to screw into the receptacle normally provided in each cylinder for a glow plug. The unit includes a piezoelectric element which is held under tension by a conductive rubber plug which coacts with a coaxial connector in transmitting the pressure indicative output signal. The transducer develops an electrical signal which varies in accordance with the pressure-time characteristic of the cylinder combustion chamber, the electrical signal representing performance of each cylinder being processed individually to provide timing and other valuable information or being combined with electrical signals developed for other cylinders of the engine in a comparative diagnostic system.

Abstract: An improved SAW pressure sensor structure includes a dual substrate sensor having a SAW substrate with a SAW delay line disposed in an active signal region on a first one of two parallel major surfaces thereof, and having a centrally apertured base substrate of the same material bonded at a mating surface thereof to the second one of the SAW substrate major surfaces with a glass seal, the dual substrates being bonded in crystallographic orientation, the central aperture having segmented portions to provide a major diameter opening at the mating surface coextensive with the active signal region to form a diaphragm and having a minor diameter opening at a second surface of the base substrate at a value less than one half that of the major diameter, the base substrate further including an O-ring groove adapted to receive one end of a cylindrical metal sleeve in a vacuum sealing relationship, the metal sleeve having a diameter equal to one half that of the aperture major diameter, the sleeve being bonded at anoth

Abstract: A transducer comprising a piezoelectric measuring sensor element for measurement of mechanical values on hollow bodies, especially of the pressure distribution within pipes, the piezoelectric sensor element being a flexible piezoelectric film, the opposite surfaces of the film being in connection with electrically leading contact surfaces, and the measuring sensor element being at least partially and at least indirectly closely joinable to the surface of the hollow body.

Abstract: The invention relates to a piezoelectric quartz force transducer having the shape of a double-ended tuning fork.

Abstract: There is disclosed an electromechanical transducer of the type employing a semiconductor diaphragm. The diaphragm is associated with an active area upon which is mounted at least one force responsive element. Surrounding the active area of the diaphragm is an annular ridge which is located on a surface opposite that containing the element. A cylindrical housing having a central aperture is secured to the diaphragm on the same surface as the element and with its aperture coaxially aligned with the active diaphragm area. The aperture in the housing being larger than the aperture of the annular ridge and underlies the same to provide an exposed area about the periphery of the element's active area. This area is used for the deposition or location of terminals which are coupled to the element. The area is insensitive to applied force due to relative size of the ridge and housing and thus conducting leads attached to the terminals do not interfere with the specifications associated with the transducer.