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Title: Capacitive proximity sensor

Abstract

A proximity sensor based on a closed field circuit. The circuit comprises a ring oscillator using a symmetrical array of plates that creates an oscillating displacement current. The displacement current varies as a function of the proximity of objects to the plate array. Preferably the plates are in the form of a group of three pair of symmetric plates having a common center, arranged in a hexagonal pattern with opposing plates linked as a pair. The sensor produces logic level pulses suitable for interfacing with a computer or process controller. The proximity sensor can be incorporated into a load cell, a differential pressure gauge, or a device for measuring the consistency of a characteristic of a material where a variation in the consistency causes the dielectric constant of the material to change.

Inventors:
 [1]
  1. (Aiken, SC)
Publication Date:
Research Org.:
WESTINGHOUSE SAVANNAH RIVER CO
OSTI Identifier:
869327
Patent Number(s):
US 5315884
Assignee:
United States of America as represented by United States (Washington, DC) SRS
DOE Contract Number:
AC09-89SR18035
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
capacitive; proximity; sensor; based; closed; field; circuit; comprises; oscillator; symmetrical; array; plates; creates; oscillating; displacement; current; varies; function; plate; preferably; form; pair; symmetric; common; center; arranged; hexagonal; pattern; opposing; linked; produces; logic; level; pulses; suitable; interfacing; computer; process; controller; incorporated; load; cell; differential; pressure; gauge; device; measuring; consistency; characteristic; material; variation; causes; dielectric; constant; change; proximity sensor; displacement current; load cell; dielectric constant; process control; differential pressure; pressure gauge; process controller; sensor based; symmetrical array; pulses suitable; circuit comprises; closed field; field circuit; common center; current varies; /73/324/

Citation Formats

Kronberg, James W. Capacitive proximity sensor. United States: N. p., 1994. Web.
Kronberg, James W. Capacitive proximity sensor. United States.
Kronberg, James W. Sat . "Capacitive proximity sensor". United States. doi:. https://www.osti.gov/servlets/purl/869327.
@article{osti_869327,
title = {Capacitive proximity sensor},
author = {Kronberg, James W.},
abstractNote = {A proximity sensor based on a closed field circuit. The circuit comprises a ring oscillator using a symmetrical array of plates that creates an oscillating displacement current. The displacement current varies as a function of the proximity of objects to the plate array. Preferably the plates are in the form of a group of three pair of symmetric plates having a common center, arranged in a hexagonal pattern with opposing plates linked as a pair. The sensor produces logic level pulses suitable for interfacing with a computer or process controller. The proximity sensor can be incorporated into a load cell, a differential pressure gauge, or a device for measuring the consistency of a characteristic of a material where a variation in the consistency causes the dielectric constant of the material to change.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 1994},
month = {Sat Jan 01 00:00:00 EST 1994}
}

Patent:

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  • A proximity sensor based on a closed field circuit is disclosed. The circuit comprises a ring oscillator using a symmetrical array of plates that creates an oscillating displacement current. The displacement current varies as a function of the proximity of objects to the plate array. Preferably the plates are in the form of a group of three pair of symmetric plates having a common center, arranged in a hexagonal pattern with opposing plates linked as a pair. The sensor produces logic level pulses suitable for interfacing with a computer or process controller. The proximity sensor can be incorporated into amore » load cell, a differential pressure gauge, or a device for measuring the consistency of a characteristic of a material where a variation in the consistency causes the dielectric constant of the material to change. 14 figs.« less
  • A semi-analytical model for a double-plate capacitive proximity sensor is presented according to the effective theory. Three physical models are established to derive the final equation of the sensor. Measured data are used to determine the coefficients. The final equation is verified by using measured data. The average relative error of the calculated and the measured sensor capacitance is less than 7.5%. The equation can be used to provide guidance to engineering design of the proximity sensors.
  • This invention is comprised of a proximity sensor based on a closed field circuit. The circuit comprises a ring oscillator using a symmetrical array of plates that creates an oscillating displacement current. The displacement current varies as a function of the proximity of objects to the plate array. Preferably the plates are in the form of a group of three pair of symmetric plates having a common center, arranged in a hexagonal pattern with opposing plates linked as a pair. The sensor produces logic level pulses suitable for interfacing with a computer or process controller. The proximity sensor can bemore » incorporated into a load cell, a differential pressure gauge, or a device for measuring, the consistency of a characteristic of a material where a variation in the consistency causes the dielectric constant of the material to change.« less
  • A liquid level sensor based on a closed field circuit comprises a ring oscillator using a symmetrical array of plate units that creates a displacement current. The displacement current varies as a function of the proximity of a liquid to the plate units. The ring oscillator circuit produces an output signal with a frequency inversely proportional to the presence of a liquid. A continuous liquid level sensing device and a two point sensing device are both proposed sensing arrangements. A second set of plates may be located inside of the probe housing relative to the sensing plate units. The secondmore » set of plates prevent any interference between the sensing plate units.« less
  • A liquid level sensor based on a closed field circuit comprises a ring oscillator using a symmetrical array of plate units that creates a displacement current. The displacement current varies as a function of the proximity of a liquid to the plate units. The ring oscillator circuit produces an output signal with a frequency inversely proportional to the presence of a liquid. A continuous liquid level sensing device and a two point sensing device are both proposed sensing arrangements. A second set of plates may be located inside of the probe housing relative to the sensing plate units. The secondmore » set of plates prevent any interference between the sensing plate units. 12 figs.« less