Showing papers on "Capacitive sensing published in 1969"

Highly Sensitive Capacitive Pressure Gauge

Abstract: Two capacitive pressure gauges which have been used extensively in the study of liquid and solid helium are described. The first gauge, constructed of Be–Cu, has a sensitivity of Δp∼2×10−6 atm for pressures of 100 atm. It is highly stable, has essentially no hysteresis, and is affected very little by changes in temperature below 4.2 K. The second gauge is of nylon construction and is suitable for NMR or with paramagnetic salt thermometry. A detailed description of the construction and use of both gauges is given.

Electrical weighing apparatus using capacitive flexible mat

Abstract: Weighing apparatus is disclosed comprising electronic circuitry and a weighing mat adapted to be loaded by a force to be measured. The mat is composed of layers of electrically conductive elastomeric material separated by strips of dielectric elastomeric material to form an electrical capacitor whose capacitance varies linearly with the application of a load to the mat. The particular arrangement of the dielectric strips in the preferred embodiment serves to extend the effective linear range of capacitive variation of the mat. Electronic circuitry is also provided to measure the variation of capacitance of the mat when the mat is loaded and to give an indication corresponding to the magnitude of the load.

Melting curve and related thermodynamic properties of He3 below 1°K

Abstract: Measurements of the melting curve of He3 have been made between 16.6° mK and 0.7°K. The liquid and solid molar volumes at melting have been extended from 0.33°K to below 0.03°K, and the molar volume change on melting ΔVm obtained. An increase in ΔVm from 1.20 cm3/mole at 0.33°K to 1.28 cm3/mole at 0.06°K is found, with an extrapolation to 1.27 cm3/mole atT=0. Examination of the thermodynamic consistency of the data indicates that our melting curve slopes are accurate, within experimental error, down to a temperature of 0.04°K. The demagnetization apparatus is described, with considerable attention devoted to thermometry, thermal equilibrium, and experimental techniques. Construction details of the high-sensitivity capacitive strain gauge are given.

Measurement of the distribution of surface electric charge by use of a capacitive probe

Abstract: A concentric, guarded probe assembly suitable for measurements of the distribution of static electric charge density on dielectric surfaces is described. The procedure for calibrating the probe is given. Application of the device is illustrated by studies of the density of electric charge on a perspex surface.

Capacitive voltage divider

Abstract: A capacitive voltage divider arrangement for driving a position transducer. Individual ones of a first plurality of individual capacitor plates are respectively capacitively coupled to individual ones of a second like plurality of capacitance plate areas, the second plurality of capacitive areas being conductively connected together and varying in area from plate area to plate area. Individual ones of a third plurality of capacitance plate areas, which are conductively connected together, are likewise respectively capacitively coupled to individual ones of the first plurality of plates. The voltage distribution on a plurality of position sensing grid lines, individual ones of which are connected to respective individual ones of the first plurality of plates, varies in accordance with the varying in areas from plate area to plate area of the second plurality of plate areas.

Single-rail mosfet memory with capacitive storage

Abstract: In connection with a one-device-per-bit capacitive MOSFET memory array, various topologies are disclosed for developing optimum memory storage capacitances between isolated P-regions and the fixed-potential substrate or a fixed-potential line. In particular, a fixed-potential line can be dispensed with, while retaining the improved capacitance associated therewith, by arranging the cells in pairs and cross-coupling them to one another. Particular clocking sequences and switching arrangements apposite to the cell topologies involved are also disclosed.

A novel proximity gauge

Abstract: A capacitive proximity gauge is described, which has a novel configuration of electrodes and makes use of the fringing capacitance between them. The device is shown to have certain advantages, particularly in the linearity of its output and the down-grading permissible in the performance of connecting leads. The variation of characteristics with geometrical details has been established experimentally, allowing optimum designs to be made to meet any chosen performance specification.

System for responding to changes in capacitance of a sensing capacitor

Abstract: Capacitive transducer system utilizing capacitive probe connected in feedback loop of operational amplifier provided with shielding system to convert capacitive changes at the probe to linear voltage changes for display by a voltmeter with the system being isolated and shielded from the effects of stray capacity.

Standardization of dielectric materials gauges having capacitive probes with remotely controlled balancing circuits using varactors

Abstract: Disclosed is a system for measuring moisture content of a sample with a capacitive probe wherein a voltage controlled, semiconductor capacitor is employed for balancing out the probe capacitance when the probe is removed from the sample. The amount of unbalance produced by the presence of the sample is used as a measure of the moisture content. The probe, capacitor and a phase inverting means are mounted in a head positioned in proximity to the sample. At a remote location from the head and sample, AC and DC power sources are provided for exciting the probe and controlling the capacity of the variable capacity semiconductor, respectively. Monitoring means for variable signals derived from the capacitance measuring means is provided. Balance is attained manually or automatically, according to different embodiments. In automatic balancing, the probe output is modulated with a predetermined frequency which is phase detected to control the amplitude of the voltage applied to the semiconductor capacitor.

Aperiodic tapered corrugated waveguide filter

Abstract: A waveguide band-pass filter utilizes a sequence of capacitive irises to form corrugations within the rectangular waveguide. The capacitive irises are aperiodically spaced along the guide and the capacitance of consecutive irises in the sequence are of different values. The waveguide has its height tapering in steps and each capacitive iris in the sequence is situated between waveguide sections of different heights.

Rotating body having combined power generating and signal coupling system

Abstract: A rotatable member is disposed for rotation in proximity with a stationary body, the rotatable member having an annular capacitive plate adapted for rotation immediately adjacent a plurality of magnetic teeth on the stationary body, the teeth and the annular plate forming a capacitor for coupling signals between the stationary body and rotatable member. At one point in the annular member is a magnetic head having a winding, the magnetic head passing over successive ones of the magnetic teeth generating electric current which is utilized on the rotating body to operate a transducer circuit, the output signal of which is coupled back through the capacitive coupling formed by the teeth in the annular surface to monitoring equipment located on the stationary body. The transducer circuit may include a power rectifier and voltage regulator which operates strain gauges, amplifiers and voltage control oscillators, the outputs of the voltage control oscillators may be multiplexed in the mixer prior to returning as a signal through the capacitive coupling.

Noncontacting displacement transducer including an oscillator with cable-connected inductive probe

Abstract: Disclosed is an eddy-current-type noncontacting displacement transducer and gage for gaging the distance between a probe tip and a metallic surface. The transducer comprises a modified common base transistor oscillator incorporating the probe coil as the oscillator resonant circuit. The base is unbypassed to increase linearity and operation at low frequency, i.e. 25 kHz. reduces capacitive sensitivity so that the transducer may be used with long cables.

Gaslamp lead ballast circuit having feedback control

Abstract: Lead ballast circuits for operating gas discharge lamps are disclosed. The circuits employ a variable inductor, such as a linear inductor or saturable reactor, in series with a capacitor as the means for limiting the lamp current. The effective impedance of the circuit is basically capacitive and the variable inductor is used to vary that effective capacitance. A feedback path between a lamp and saturable reactor is also disclosed.

Mass fuel flow measurement system

Abstract: The system measures the mass flow rate of a liquid. It comprises a turbine impeller located in the flow stream which rotates at a rate proportional to the volume flow rate of the liquid and produces a corresponding electrical signal. This electrical signal is electrically multiplied with a further signal proportional to the liquid density so as to give the required liquid mass flow rate. The density signal is obtained from a capacitive sensor positioned in the liquid whereby the liquid constitutes the dielectric of the capacitor so that the capacitance of the sensor varies with density.

Cyclic device for analog to digital conversion

Abstract: IN A CIRCULATING OR CYCLIC DEVICE, FOR CONVERTING ANALOG DATA TO DIGITAL FORM, A CAPACITIVE TRANSFER TECHNIQUE IS PROVIDED FOR ACCOMPLISHING SUCH CONVERSION. IN ADDITION, A CAPACITIVEREFERENCE VOLTAGE SWITCHING TECHNIQUE, PARTICULARLY FOR CYCLIC CONVERTERS IS PROVIDED FOR PRESENTING A BIPOLAR REFERENCE SWITCHING EFFECT UTILIZING A UNIPOLAR REFERENCE.

Capacitive displacement transducer

Abstract: A capacitive position transducer comprising two cylindrical coaxial reference electrodes disposed side by side, and a coaxial cylindrical movable electrode disposed within the reference electrodes for movement along the axis to vary the capacitive couplings between the moving electrode and the respective reference electrodes as functions of position. Flanges at each end of the moving electrode are maintained at ground potential and project towards the reference electrodes to form guard rings. One or more screws of conductive or insulating material project through the guard rings to adjust the capacitive couplings. The reference electrodes are spaced from a housing, and the moving electrodes from a shaft, by three-point bearings formed by sapphire balls.

Antiglare coating for cathode-ray tube used with capacitive coupled voltage pen

Abstract: A multilayer optical transparent coating in conjunction with a circular polarizer that reduces glare and provides capacitive coupled voltage pen action. The transparent multilayer antireflective coating circular polarizer structure permits visual observation of the information on the face of the cathoderay tube with minimum glare and reflection and also maintains a potential field across one of the layers of the antireflective coating. The potential field is utilized for correlating a pen position on the outer surface of the multilayer coating.

Continuous sputtering system

Abstract: In a system for depositing thin films of material on a workpiece by a technique known as radiofrequency sputtering, an electrical transformation bridge comprised of inductive and capacitive components is electrically interfaced between an unbalanced output of a radiofrequency generator and the excitation electrodes of a sputtering chamber for converting the generator output signal into opposing phase radiofrequency voltage components employed in preferred continuous sputtering systems and for precisely matching the impedance output of the generator with the impedance of the excitation electrodes while the latter are under the influence of a plasma of charged deposition particles.

Voltage controlled oscillator in which capacitive diodes become resistive during portions of each cycle

Abstract: By varying the voltage applied to two oppositely poled varactors, placed in series in the resonant circuit of a microwave oscillator, the portion of each oscillatory cycle in which each varactor acts as a capacitor as opposed to a low resistance, is varied, thereby linearly varying the oscillatory frequency of the circuit.

Paramagnetic gas sensor having capacitive position sensing and ac null balancing feedback

Abstract: Apparatus for determining the partial pressure of a paramagnetic gas in a gas mixture wherein a pivotally mounted test body is supported in an inhomogeneous magnetic field, the test body being deflected from a null position when the paramagnetic gas is present, the improvement wherein an AC bridge circuit is utilized, in response to deflection of the test body from the null position, to generate an AC signal indicative of the partial pressure of the paramagnetic gas. The bridge circuit comprises a pair of electrostatic vanes which, in conjunction with the test body, form capacitive elements of the bridge circuit. The AC signal is either measured to determine the test body position, or demodulated to provide a DC signal. The DC signal may be fed back to the bridge circuit to return the test body to the null position for improved linearity and stability. Apparatus is further provided to vary the fraction of the DC signal fed back to the bridge circuit with changes in temperature of the test body to compensate the apparatus for temperature variations.

High frequency coaxial filter

Abstract: A high frequency coaxial line filter is disclosed. The filter includes a section of coaxial line containing an input resonator and an output resonator decoupled by a decoupling capacitive structure disposed therebetween. The resonators each include an inductor having a central hub with radially directed inductive spokes extending from the hub to the outer conductor of the coaxial line. Capacitors for the circuit are formed by capacitive gaps formed between the ends of the hub portions of the inductors and adjacent conductive structure.

Position responsive variable capacitor

Abstract: A CAPACITIVE POTENTIOMETER IN WHICH THE ELECTRIC FIELD IS SET UP BY AT LEAST TWO ELECTRICAL DISCRETE ELEMENTS DISPOSED IN A LINE AND THE ELECTRODE AND ELEMENTS ARE MOVABLE RELATIVELY ALONG SUCH LINE AND WHEREIN THE OPERATIVE ELECTRIC FIELD PASSES THROUGH ONLY ONE DIELECTRIC TO AVOID UNSYMMETRICAL DISTORTION OF THE FIELD DUE TO ENVIRONMENTAL CHANGES.

Filter switching circuit

Abstract: A filter switching circuit including a plurality of inductive and capacitive circuit elements. In one position of a twoposition switch all of the circuit elements are connected to form a band-pass filter between an input and an output. In the other position of the switch the same circuit elements are connected to form a band-stop or band rejection filter.

Apparatus for capacitively sensing information apertures in data cards

Abstract: Card reading apparatus comprising a plurality of input conductors for disposition along one side of a data card incorporating an electric shield and a plurality of readout conductors for disposition along the opposite side of the card to establish a capacitive coupling between the readout conductors and the input conductors through selectively positioned apertures in the shield representing recorded information. A plurality of voltage stabilizing capacitors have output sides connected to the respective readout conductors. A plurality of voltage stabilizing amplifiers have inputs connected to the respective readout conductors and outputs connected to the input sides of the respective capacitors. Information receiving means is coupled to the input side of each capacitor to respond to the change in voltage applied thereto by the corresponding amplifier upon energization of an input conductor to which the corresponding readout conductor is coupled capacitively through an aperture in the electric shield. The capacitance of each capacitor and the gain of each amplifier operate together in response to an incipient change in voltage on the corresponding readout conductor to restore continuously the original voltage on the conductor so that the input to the information receiving means is not rendered inaccurate by spurious and parasitic capacitive relationships of the readout conductors to adjacent structure.

Capacitive detector for a ram movable on a frame

Abstract: A capacitive detector for a ram of a press hammer where a rod forms one electrode of the capacitor and the wall of a bore forms the other electrode of the capacitor, the rod and bore being arranged so that one can move with the ram and the other is joined to a stationary frame.

Composite dielectric body containing an integral region having a different dielectric constant

Abstract: IN THE FABRICATION OF MICROELECTRONIC CIRCUITRY, A CAPACITIVE DEVICE IS FABRICATED COMPRISING A DIELECTRIC MATRIX THAT INCLUDES A DISCRETE REGION AUTOGENOUSLY FORMED THEREIN HAVING A DIELECTRIC CONSTANT THAT DIFFERS FROM THAT OF THE MATRIX.

Electronic testing apparatus

Abstract: A testing apparatus for logic circuit devices comprising a buffer amplifier pulse driver for driving capacitive loads with fast rise and fall times and for producing programmable output pulses at predetermined levels and in accordance with a predetermined logic pattern. The apparatus comprises a pair of operational amplifiers each adaptable to receive an input at a level equal to the desired output pulse. Each of the amplifiers has an output driver stage with an input connected to and driven by a current switch adaptable to receive a controlling logic input pulse in the same pattern desired at the apparatus output which is connected to the device being tested. The current switch provides the necessary drive to enable the output driver stages to bring the output to the desired level, and once that level is reached during each transition it is held constant by the operational amplifier until the next transition pulse from the logic input. The driver switches function to provide the pulse transitions to and from predetermined levels independent of the operational amplifiers and to hold the output at the desired level in conjunction with their operational amplifier.

Integrating circuit using a programmable unijunction transistor

Abstract: A unique integrating circuit adapted for use in conditionresponsive systems for preventing false alarming due to a series of rapidly occurring transient signals. A programmable unijunction transistor is used to rapidly discharge the capacitive element of the integrator in response to a slight decrease in input signal.