Showing papers on "Capacitive sensing published in 1972"

Electronic switch actuated by proximity of the human body

Abstract: An improved contact-less electronic switch, adapted to be actuated by the approach of a human hand, with a capacitive probe insulated against the chassis and installed in the zone of approach, and connected to a capacitance detecting circuit which delivers a switching signal when the capacitance is increased by the approach of a hand, wherein the improvement comprises that the switch remains unaffected by the approach of all other substances, such as metals or insulating materials

Capacitance matrix keyboard

Abstract: An electronic system having a keyboard for entry of digitally coded data on a carrier wherein capacitive switches operated by the keyboard program a matrix which is scanned to produce digitally coded data trains.

Pressure sensitive transducers employing capacitive and resistive variations

Abstract: There is disclosed a pressure transducer assembly which employs a flexible thin diaphragm. The diaphragm serves a dual purpose as a moveable plate of a capacitor and a support for a force responsive element. The force responsive element is coupled to the capacitor to form a composite circuit network, which network exhibits a dual impedance variation proportional to diaphragm deflection.

Rf sputtering apparatus and method

Abstract: An RF bias sputtering apparatus is provided having simple on-off operation in which there is no detuning of the apparatus to an RF power source when sputtering conditions within the ionization chamber change. The capacitive reactances within the chamber and without the chamber are divided into a reactance bridge network, a capacitive reactance means being disposed across an arm of the bridge for balancing the reactances of the bridge network. Critical tuning requirements are reduced by the use of an RF power source with wide bandwidth tuning capabilities.

Capacitive position sensor

Abstract: A capacitive rotor position sensor generates three phase output pulses indicative of the position of the rotor of a three phase commutatorless D.C. motor. A radially elongated capacitor plate connected to the motor rotor is rotatably mounted adjacent 12 circumferentially displaced stationary capacitor plates, and a high frequency oscillator is coupled to the rotatable plate. A differential amplifier for each phase has one input coupled to three adjacent first stationary capacitor plates which together subtend 180 electrical degrees and the other input coupled to three adjacent second stationary capacitor plates which together subtend 180 electrical degrees and are displaced 180 electrical degrees from the first plates, and the corresponding inputs of the three differential amplifiers are coupled to first stationary plates displaced 120 electrical degrees apart and to second stationary plates displaced 120 electrical degrees apart. The high frequency pulses from the oscillator are coupled through the rotatable plate to the stationary plates, and the differential amplifiers enhance the one-to-zero ratio of (1) a logic one signal from a stationary plate opposite the rotatable plate at a given instant; and (2) a logic zero signal from a stationary plate simultaneously displaced 180 electrical degrees from the rotatable plate, to derive square wave output pulses at a frequency proportional to motor speed indicative of the rotor position.

Antenna for airborne satellite communications

Abstract: A broadband VHF/UHF antenna exhibiting a hemispherical radiation pattern comprising four orthogonally positioned radiating elements and means for feeding the elements in phase quadrature. Each element includes a vertical blade portion and a capacitive loading section attached to the upper edge of the blade portion. The capacitive loading portions define at least approximately a spherical section.

Environment immune high precision capacitive gauging system

Abstract: A capacitive probe having at least two electrically conducting probe tips or electrodes centrally placed within an electrically conducting housing and axially displaced from each other within the housing. A physical dimension is measured by determining the capacitance between one probe tip and a surface, the capacitance therebetween varying with the dimension being measures. Precise machining of planar probe tips and assemblies to make them identical, their close placement, and the use of a moisture impenetrable dielectric for supporting the tips within the housing insure precision measurement and environmental independence. This precision and its maintenance is augmented by electronic excitation circuitry for the probe tips which maintain the instantaneous electric potential on each tip approximately equal and which gives an output signal whose average variation from a ground or common potential is directly indicative of the distance being gauged. Modifications to the basic probe construction include: provisions for guarding each probe tip with a substantially equal potential: thin or thick film deposition probe tip constructions; and probes having a plurality of tips for sensing a multiplicity of factors influencing the capacitance between the probe and a surface with circuits for separating the factors. A specific application of this for dielectric strip width measurement is presented.

Information playback system

Abstract: Information is recorded as capacitive variations in a spiral groove on a disc record. The capacitive variations are detected by a tracking stylus and coupled to a stage including a source applying signals to a tuned circuit. The detected capacitive variations cause signals modulated by the record information to develop in the tuned circuit. The stage is controlled so that a predetermined relationship is maintained between the signals applied to the tuned circuit and the tuned circuit response. The tuned circuit may include a transmission line to minimize the total shunt capacity of the circuit. This increases the percentage modulation of the signals developed in the tuned circuit by increasing the ratio of the detected capacitive variations to the total shunt capacity of the tuned circuit.

Radio frequency electrically excited flowing gas laser

Abstract: Apparatus for producing laser action in a flowing gas by electromagnetic energy at radio frequencies wherein the discharge circuit is capacitively ballasted by providing capacitive impedance between the electrode and the gas.

Antenna with large capacitive termination and low noise input circuit

Abstract: An antenna having a short stem and a larger than normal capacitive termination to provide improved performance over antennas of the same effective electrical length, and an input circuit having a larger than normal total input resistance for obtaining improved signal-to-noise ratios by using the capacitive reactance of said antenna as a noise sink.

Nonvolatile capacitive memory cell

Abstract: The present invention relates to a nonvolatile capacitive memory cell, which has a capacitive means and a nonvolatile alterable threshold field effect transistor therein. The nonvolatile alterable threshold field effect transistor is used to capacitively store information in said capacitive means while power is applied to the nonvolatile capacitive memory cell. The nonvolatile alterable threshold field effect transistor is also used to nonvolatilely store a binary bit of information which is capacitively stored within the capacitive means, when power is lost to the nonvolatile capacitive memory cell. A pulse from a storage driver connected to the gate electrode of the nonvolatile alterable threshold field effect transistor causes the nonvolatile storage of said binary bit of information. When a binary one bit of information is capacitively stored in the volatile capacitive means, and power is lost, the threshold voltage of the nonvolatile alterable threshold field effect transistor will not be changed, representing the nonvolatile storage of a one bit by said transistor. When a binary zero bit of information is capacitively stored in the volatile capacitive means and power is lost, the threshold voltage of the nonvolatile alterable threshold field effect transistor will be changed, representing the nonvolatile storage of a zero bit by said transistor. A write data circuit is connected to the source electrode of the nonvolatile alterable threshold field effect transistor to capacitively store a binary bit of information into the capacitive means. A preset circuit and a storage circuit are used in nonvolatilely storing the one or zero bit of binary information of the capacitive means into the nonvolatile alterable threshold field effect transistor as power is lost to the nonvolatile capacitive memory cell.

Low power fet driver circuit

Abstract: Disclosed is an FET (field effect transistor) driver circuit capable of driving large capacitive loads, while dissipating relatively little power. A delay circuit forms a parallel path between the circuit input and output providing a delayed signal at the output of the circuit after the gate to source feedback capacitor of the output FET has been charged. The particular delay circuit disclosed herein accurately tracks the driver circuit providing a precise time delay for limiting transient power dissipation in high frequency operation.

Capacitive probe structure for testing the integrity of electrical cables and conductors

Abstract: This invention relates to a probe structure designed to be capacitively coupled to an insulated electrical cable or conductor, and which is operative to pick up relatively weak electrical signals induced on or carried by a selected part of the cable or conductor, and to convert said signals into output voltages capable of audible or scientific measurement.

Improved bucket brigade delay line

Abstract: A capacitive delay device comprising a sequence of capacitances which have been interconnected by the series arrangement of the main current paths of at least two transistors, the capacitance of the capacitor connected between the output and control electrodes of the first transistor being as small as possible.

Capacitive electrical connectors

Abstract: Electrical connectors, such as of a type useful for connecting circuit cards or modules to other electronic equipment, are disclosed herein. An exemplary connector includes an electrically conductive block adapted to be physically and electrically coupled with a circuit board and removably connected with respect to a second electrically conductive block. The latter block is adapted to be coupled to various electrical conductors, such as coaxial cables, ground and power plugs, or the like. The blocks are mounted in capacitive relationship and are also electrically connected to provide a direct current path.

Bucket bridge delay line with error compensation

Abstract: A capacitive delay device comprising a sequence of capacitances, in which information is transferred by charge transfer. The device is provided with at least one auxiliary store which has been connected between a first and a second capacitance, whilst after a charge transfer between the capacitances a residual charge transfer takes place between the first capacitance and the auxiliary store, after which the charge stored in the auxiliary store and in the second capacitance is transferred to a capacitance succeeding the second capacitance.

Means for measuring loss tangent of material for determining moisture content

Abstract: A-c voltage is applied through two branches to respective input circuits of a phase detector. One of the branches includes a controlled phase shifter and a capacitive impedance circuit; the capacitive impedance circuit includes a moisture test cell and in the usual manner provides phase shift dependent upon the permitivity and loss factor of material placed in the moisture test cell. The overall shift in phase of the voltage in this branch of the circuit is therefore determined by the sum of the phase shift in the controlled phase shifter and the phase shift in the capacitive impedance circuit dependent on the sample in the moisture tester. The output of the phase detector is applied to a d-c control circuit of the controlled phase shifter to control the phase shift such that the sum of the phase angles of the phase shifter and the capacitive impedance circuit is maintained at a predetermined constant. The voltage on the output circuit for controlling the phase shifter is also the voltage that is applied to an indicator to determine moisture content according to the loss tangent of the material being tested. The output readings are substantially independent of the densities of the materials placed in the test cell.

Active delay-equalizer network

Abstract: An active delay-equalizer network which utilizes only two operational amplifiers and a number of resistive or capacitive components to provide a second-order network. The circuit has a low impedance output and hence is readily connected in tandem.

Flow metering system for liquid wastes

Abstract: A liquid flow metering system comprising a flow conduit, many of such conduits having a dielectric lining supported for strength by a moisture bearing material such as concrete, the concrete itself often having still other moisture bearing material on the outside of it such as dirt, a capacitive electrode imbedded in or attached to a side wall of the conduit, a dielectric medium disposed between the capacitive electrode and the moisturebearing concrete, dirt or other material, the dielectric medium being disposed on the side of the capacitive electrode which faces away from the center of the conduit to prevent the capacitive electrode from sensing the moisture in the concrete, dirt, or other moisture-bearing material whereby the capacitive electrode senses only liquid in the conduit so as to give accurate sensing thereof.

RF biasing through capacitive collector to target coupling in RF diode sputtering

Abstract: An RF sputtering system which is suitable for deposition of both conductive and nonconductive thin films by bias sputtering is described. The substrate bias is obtained by capacitive collector to target coupling, the capacitance of the collector dark space and an external capacitor being used for voltage division. The influence of target voltage and sputtering pressure on bias generation is considered. When using RF discharge no electrode is in direct electric contact with the plasma, and a systematic error is introduced by measuring the bias voltage as collector DC voltage relative to the target's earthed counter electrode, which error is discussed. Data are presented on the temperature coefficient of resistance in bias-sputtered nickel films showing similar dependence on target voltage and on bias voltage.

Condition responsive circuit with capacitive differential voltage

Abstract: A condition responsive circuit, disclosed as including a temperature responsive element, is adapted to be connected to by a pair of terminals by an alternating current load and to a source of alternating current voltage. The condition responsive circuit operates through a differential amplifier to control a solid state switch, shown as a silicon controlled rectifier. This solid state switch in turn operates further solid state switching to control the load. A capacitor for creating a differential voltage in the input circuit of the differential amplifier is connected by a discharge circuit to the silicon controlled rectifier so that the voltage on the capacitor is discharged every time the silicon controlled rectifier is conductive.

Moisture monitor having a resistor between sensing capacitor and oscillator tuned input to improve oscillator response

Abstract: An electrical circuit provides a measurement or control in accordance with the moisture content of a specimen or sample, and includes: a capacitive cell comprising two spaced and insulated metal plates between which the specimen or sample can be placed to act as a part of a dielectric between the two plates; an oscillatory circuit to which said capacitive cell is coupled in such a manner that variations in the capacitance of the cell produces variations in the state of loading of said oscillatory circuit; and output means providing a measurement and/or a control in accordance with the said state of loading of said oscillatory circuit.

Capacitive intrusion detection system with balanced resonant circuits

Abstract: Each of a pair of detector wires is strung along a portion of a boundary to be protected so that both wires are exposed to similar general environmental conditions. The wires are interconnected in respective resonant circuits which are similarly driven at a common frequency so that each resonant circuit provides an a.c. signal having a phase and amplitude which are variable as a function of the capacitance of the respective detector wire. By synchronously demodulating the difference between the two signals, a difference amplitude signal is obtained which is relatively sensitive to differential changes in the capacitances. By employing the rate of change of this demodulating difference signal as an indication of intrusion, a system is obtained which is relatively insensitive to gradual and environmental changes.

Capacitive memory gas discharge display device having internal conductors

Abstract: A capacitive memory gas discharge display device having a pair of drive lines for each cell of the device located directly within the gaseous environment. The conductors are at least partially covered with a dielectric serving as a means of providing a uniform spacing between the wires, a means to keep the wires from shorting and a means for developing a capacitive charge from the firing of the cell, such charge providing a memory for the particular cell such that the voltage required for refiring the cell is less, by the amount of the charged voltage, than the voltage required for the initial firing.

A broad-band wide-angle scan matching technique for large environmentally restricted phase arrays

Abstract: Numerical solutions for the problem of radiation from an infinite planar array of waveguide horns loaded at the aperture with a thick partially dielectric filled inductive step plus an external radome are presented. The analysis is applied to the problem of matching a practical array over a specified scan volume and frequency band. A technique from which the best possible initial match is obtained by varying the step width and thickness is presented. The final broad-band match is obtained with the aid of two thin capacitive irises located inside the waveguides. Experimental verification of the analysis and resultant computer program used for the design is presented in the form of waveguide simulator results. Three H -plane simulators are used and comparison of theory and experiment is presented for different combinations of external and internal matching structures.

Capacitance and resistance-responsive control circuits

Abstract: Control circuits for sensing and responding to impedance changes caused by a mammal in contact with or in proximity to an antenna or other sensor. Each circuit includes at least one tuned circuit which is periodically energized to cause it to ''''ring'''' at its natural frequency, i.e., to produce damped oscillations. Each tuned circuit includes an antenna or other sensor by which an external impedance is coupled to the tuned circuit. Thus, the oscillations in the tuned circuit are attenuated to a degree determined by the capacitive and resistive components of the external impedance. In the case of mammals, the resistive component is substantial and causes a marked change in the amplitude and duration of the damped oscillations in the tuned circuit, which are then enhanced and/or detected to produce a predetermined control signal.

Devices for the measurement and control of magnetic field strength

Abstract: 1279091 Magnetometers NEWPORT INSTRUMENTS Ltd 8 Aug 1969 [8 May 1968] 21834/68 Heading G1N In a magnetometer of the type in which the force on or displacement of a current carrying conductor in the field being measured is measured, stationary capacitor plates co-operate with the conductor or a plate attached thereto for sensing displacement of the conductor. As shown in Fig.1 a current I, which may be direct alternating or intermittent, is passed through arm 15 and the torsional displacement or torsional oscillations of arms 14 and 15 is sensed by differential capacitors 16, 17 and 18, 19. If A.C. is used, its frequency may coincide with the resonance frequency of the structure 10. Excitation periods may be alternated with measurement periods. E.M.F.s induced in one or more of the conductive paths may be compared with the capacitive measurements. Electrostatic forces may be used to achieve a null balance. Part of the vane structure may be electrically isolated from the rest of the vane so that the electrical charge on this part (40) Fig.4a (not shown) remains constant whereby electrical repulsion forces may be used. Other configurations of vanes are described with reference to Figs.3a to 4a (not shown). In Fig.5, coils 55, 56 are mounted on a part 57 supported by bearings 60, 61. Leads to the coils and to capacitor plates 58, 59 may be in the form of springs controlling the position of the moving structure. In another arrangement, Fig.6 (not shown) four conductive paths (66, 67, 68, 69) are attached in pairs to opposite faces of an insulating strip (70), a respective capacitor plate being positioned opposite each path. A stationary conductive loop 77 responds to variations in time of the magnetic field.

Mechanically variable modular high reactivity power inductor for high a. c. voltage resonant testing of capacitive loads

Abstract: A mechanically variable high reactivity power inductor is described for high A.C. voltage testing capacitive loads, such as high voltage electrical power transmission cables, large capacitors, or groups of capacitors, and transmission and generation equipment.

Absorption frequency meter having shielded inductor

Abstract: An absorption frequency meter having a high-Q circuit comprising a resonant circuit having variably adjustable concentric capacitive plates, electrically in series with an inductance means and an indicating means, said capacitive plates providing electromagnetic shielding for said inductance means.

Resonator for gyromagnetic-resonance spectrometer

Abstract: In order to avoid disturbing the tuning of a resonator, formed by an essentially capacitive line and an essentially inductive Lecher line connected in series, when the sample is introduced into the resonator, the capacitive line is a coaxial line section, the inner conductor of which forms a shield against the electric field due to this line. Alternately the first capacitive line also is Lecher line but a metal tube protects the space containing the sample from the electric field due to this line.