Abstract: A technique for measuring capacitance and displacement, in which two circuits are combined, one that produces a current proportional to capacitance, and another that integrates that current between two reference levels, and supplies an output proportional to the integration time. In preferred embodiments, the first circuit is a capacitive pump circuit, and the second circuit a dual-slope integrator.

Abstract: The surface parameters and characteristics of a conductive workpiece are determined by applying a voltage between the workpiece and a capacitance probe having proximity sensing capabilities, and moving the probe in two or three co-ordinate axes relative to the workpiece while measuring the capacitance between the probe and workpiece, and controlling the probe velocity and/or direction within a stand-off band adjacent to the workpiece as a function of the capacitance value measured for purposes of effecting significant real time process controls, and determining the workpiece surface parameters as a function of the probe movement and capacitance measured.

Abstract: A wall thickness inspecting device includes a plurality of channels that generate a voltage signal as the glass container rolls along an elongated capacitance strip. A switch is provided for operation during head cleaning which isolates the data file from bottle rejection data, and from bottle inspected data count.

Abstract: A method for measuring the gap between a roller and an adjacent member in an electrophotographic printing machine is disclosed wherein a flexible sensor is provided and passed into the developer sump area in the printing machine. The flexible sensor is passed between the roller and adjacent member for measuring the distance therebetween. The flexible sensor is comprised of a capacitance sensor and a metal laminate. As the sensor is passed between the roller and adjacent member, the sensor is magnetically attracted to the roller and conforms to the circumference of the roller. The adjacent member can be a trim bar within the developer sump.

Abstract: Signal errors generated in a channel of a wall thickness inspecting machine are detected and counted to determine whether the channel should be turned off.

Abstract: A method of semiconductor surface measurement for measuring electrical characteristics of a surface of a semiconductor body is disclosed, by which an electrode, whose surface, which is opposite to the surface of a semiconductor substrate, is flat and the gap between the electrode and the surface is smaller than 0.5 .mu.m.

Abstract: This invention provides a means for restoring the output waveform of a DC capacitive tip clearance sensor 26 which has been effected by electrical noise in an ion rich environment such as for example a gas turbine engine turbine section 16. The means comprises a pair of electrodes 28,30 each of which is polarized to either a high positive or a high negative potential. The probes 28,30 are situated upstream of the sensor 26 and act to remove any charge carriers from the gas stream before the gas reaches the sensor 26. The sensor 26 may then operate without experiencing undesirable fluctuations in its voltage output.

Abstract: A capacitance-type height gage for measuring the distance between a test probe and a surface includes comparison circuitry for detecting the phase angle difference between the test probe signal and a reference signal. The reference signal having an adjustable phase angle. Phase angle comparison is achieved by multiplying the test probe signal with the reference signal and filtering the output. The filtered output is inversely proportional to the distance between the test probe and the surface. Compensation circuitry is included for cancelling stray capacitance.

Abstract: A method and structure permit the precision alignment in the packaging of optical components, such as lasers, detectors, lenses and waveguides. The technique involves capacitance measurements of an array of plates placed on the optoelectronic device chip and its package substrate. The technique uses phase sensitive detection to sense the total current capacitively coupled into a passive plate on the device chip from two overlapping plates located on the package substrate. When the device chip is properly aligned with respect to the package substrate, the summed current sensed with a third overlapping plate on the package substrate is a null.

Abstract: An electrical capacitance clearanceometer system adapted clearanceometer system to measure the distance between a housing and a moving member within and closely adjacent the housing as a function of electrical capacitance therebetween, utilizes a high temperature probe which contains a high temperature electrical inductor potted in one end and an electrical capacitor electrode in a braze sealed tip at the other end and electrically connected to the inductor. The probe is inserted in a housing to have its capacitor electrode positioned adjacent the moving member. The electrode is braze attached to a ceramic insulator at the end of the probe and the ceramic insulator is brazed to a transition metal sleeve which is then brazed to the probe to fix the insulator in the probe. An air passage is formed between the insulator and the probe body to provide cooling air to the insulator and capacitor electrode.

Abstract: In a hot gas turbine engine a capacitive probe clearanceometer is employed to measure the clearance gap or distance between the continuous surface of a compressor or turbine wheel such as, for example, a shroud ring turbine and its confining casing under operating conditions. The probe positions a capacitor electrode at the inner surface of the casing adjacent the continuous surface path. Electrical power is supplied to the probe through an oscillator having a tuned circuit in which the probe is a component. A high frequency signal of the oscillator is amplitude modulated by changes in electrical capacitance between the probe capacitor electrode and the passing continuous surface. The modulated oscillator signal is processed to provide an electrical signal which is proportional to the distance between the casing and the continuous surface. A preferred combination of high temperature and contamination resistant metal and ceramic materials are combined in an improved gas tight braze sealed probe tip.

Abstract: A capacitance probe (10) includes readily removable outer layers (64,66) which facilitate its use in the field to measure the width of slots or clearances (12) of different widths; an optionally perforated guard electrode (64,66,76,82) which permits width measurements over wider side wall bands with minimal effect on sensitivity; convergent or tapered side edges (102) to ease insertion and movement of the probe and a carrier block (124) which ensures proper positioning of the probe within such slots.

Abstract: An apparatus and method for generating microscopic scan data of C-V and/or dC/dV over a scan area. A scanning microscope, for example a scanning force microscope, is provided with a voltage biased tip, for example, of tungsten, which is scanned across an area to derive the data. The data can be used to derive a plot of semiconductor dopant level across the scan area. Other material properties can be derived, for example, carrier generation and recombination rates and subsurface defects.

Abstract: A capacitive dimensional measurement chain with linear output is essentia comprised of a capacitive sensor formed by a central detection electrode and a guard electrode surrounding the detection electrode that are respectively powered by two a.c. bias voltage sources. The chain also comprises a reference capacitor and a measuring circuit for measuring the distance between the detection electrode and a conductive part placed facing the detection electrode. The bias voltage sources are variable level sources and are level-controlled by a distance measurement signal issued by the measuring circuit. The measuring circuit comprises a level amplifier and a demodulator for amplifying and demodulating an incoming error signal representative of a difference between a load of a sensor capacitance that is defined between the detection electrode and the part separated by the distance to be measured, and a load of the reference capacitor.

Abstract: A portable level sensing device includes an audible alarm and a visual alarm (preferably LEDs) for signalling when a predetermined level has been sensed by a capacitance proximity switch. The device is designed for use in tank cars, ships, barges, and tank trucks, and includes a graduated rod and a threaded coupling to allow one to quickly and easily set the capacitance proximity switch at the proper level in a tank. The device includes an weather-tight housing and is intrinsically safe for use in hazardous area classifications Class I, Division 1, Groups A, B, C, & D. The device can be coupled in a pressuretight manner to the tank to prevent the escape of fumes during use.

Abstract: Capacitive-type measuring apparatus for making absolute measurements comprises first and second support members which are relatively displaceable with respect to a measurement axis; an array of first electrodes disposed on the first support member; an array of second electrodes disposed on the second support member such that differing portions of the second electrode array are capacitively coupled with the first electrode array in dependence on the relative positions of the support members; an array of third electrodes disposed on the second support member so as to be electrically connected to corresponding second electrodes and spatially offset therfrom by an amount which varies according to the position of the third electrodes from a reference position; and a fourth electrode arrangement disposed on the first support member for providing in combination with the other arrays a plurality of discrete signal transmission paths each having a capacitive transfer function with two components, one of which varies a

Abstract: A liquid level sensing apparatus, including a bridge circuit sensitive to an element the impedance between a liquid sample and a pipette for providing a signal corresponding to the impedance, a phase detector for phase-detecting the output signal of the bridge circuit, a high-pass filter for differentiating the phase detection signal and a circuit for inhibiting the passage of a variation component of a signal from a band-pass filter and passing a liquid level signal component.

Abstract: A phase discrimination type electrostatic capacity detector includes an one-side electrode plate composed of a transmitting electrode and a receiving electrode, another-side electrode plate having coupling electrodes and disposed relatively movably with respect to the one-side electrode plate in a confronting relation with the same, a power supply connected to the transmitting electrode, and a detector circuit connected to the receiving electrode. The detector is miniaturized by disposing the transmitting electrode in a second hierarchy layer partitioned by an electrical insulating layer on a substrate and connecting in series the respective transmitting electrode elements of the same phase in a first hierarchy layer through coupling leads. The detector including a pair of receiving electrode elements between which the transmitting element is interposed, is miniaturized by leading out the coupling leads to one side end of the one-side electrode plate through a space between both receiving electrode elements.

Abstract: The occurrence of physical contact between a conductive probe and a surface of a liquid held in a container is detected as the probe is moved toward and eventually touches the liquid surface; a conductor is disposed on the other side of the container from the probe; an electrical signal is sent through the liquid between the conductive probe and the conductor, and the time when physical contact has occurred is determined based on when the resulting electrical signal which has passed through the liquid exceeds a threshold; and the threshold is determined based on the resulting electrical signal. In another aspect, the electrical signal is pulsed, and the resulting electrical signal is synchronously detected as the basis for determining when the physical contact has occurred.

Abstract: Apparatus for determining an overall dimension of an electrically conductive object includes a support surface for receiving the object, an electrically conductive plate movable toward and away from the support surface along a path normal to such surface, the plate having a facing surface which faces the support surface and a voltage source for applying first and second electrical potentials to the object and the plate, respectively, to establish a voltage therebetween. A transducer is provided for developing a distance signal representing the distance between the facing surface and the support surface. A motor moves the plate toward the object while the object is received by the support surface and circuitry is provided for detecting when the voltage between the object and the plate disappears due to contact of the plate with the object whereby the distance signal at such time is representative of the overall dimension.

Abstract: Capacitive-type measuring apparatus for making absolute measurements comprises first and second support members which are relatively displaceable with respect to a measurement axis; an array of first electrodes disposed on the first support member; an array of second electrodes disposed on the second support member such that differing portions of the second electrode array are capacitively coupled with the first electrode array in dependence on the relative positions of the support members; an array of third electrodes disposed on the second support member so as to be electrically connected to corresponding second electrodes and spatially offset therefrom by an amount which varies according to the position of the third electrodes from a reference position; and a fourth electrode arrangement disposed on the first support member for providing in combination with the other arrays a plurality of discrete signal transmission paths each having a capacitive transfer function with two components, one of which varies

Abstract: A distance-measuring apparatus for measuring the distance between a capacitance-type sensing probe (60) and a nearby surface of a conductive body is provided. A probe (60) includes a plurality of measuring electrodes (56.sub.l -56.sub.n) and a grounding electrode (58). The grounding electrode protrudes from the probe and grounds the nearby surface of the conductive body. A control system (10) is connected to the probe (60). A processor (12) issues control instructions, S.sub.CTL, to a selector (16). The selector (16) selects one of a plurality of measuring electrodes (56.sub.l -56.sub.n) and connects the selected electrode to a converter (14). A charging circuit (18) applies a charging voltage to the selected electrode, causing a capacitor formed by the selected electrode and the nearby surface of the conductive body to charge up. A timing circuit (22) starts a counter (32) when one of the measuring electrodes (56.sub.l -56.sub.n) is selected and stops the counter (32) when a capacitor charge voltage, V".sub.

Abstract: A method and apparatus for determining the extent of deflections of a movable diaphragm in a capacitive displacement type transducer. The transducer circuit is connected to a three terminal capacitive type transducer, and produces an output which is essentially of stray capacitances, circuit component tolerances and changes, and dimensional changes in the transducer elements caused by temperature changes. This is achieved by providing an output which is representative of the difference in the capacitances of the two transducer capacitors, nominalized by dividing by the sum of the capacitance reciprocals. The output of the transducer circuit thus represents the extent of the diaphragm deflection with all other transducer and circuit parameter variations removed.

Abstract: A capacitance sensor arrangement is used to determine the distance of an element such as a shearing handpiece from a surface such as the skin of a sheep. The arrangement processes data from one or more sensors which include a variable capacitor dependent on the distance, and provides an output voltage consistent with the distance, the output voltage being dependent on the voltage drop across a reference capacitor in the sensor circuit.

Abstract: An electrostatic angle resolver has a stator for producing a patterned electrostatic field, a rotor having sensivitity to the electrostatic field, a capacitive coupling providing a signal interconnection between the rotor and the stator, and an active shield supplied with a voltage signal substantially identical to that signal present on the stator thereby diminishing degradation in the strength of the signal coupled between the rotor and the stator.

Abstract: A probe (20) that inspects a countersunk hole (21) in a conductive body, such as an aircraft part (22), is provided. A plurality of nested cylinders form an electrode cartridge (54) with a countersink portion (74) having a frustoconical shape and a hole portion (76) having a cylindrical shape. A plurality of lower hole electrode strips (72) are mounted on a lower hole cylinder (110) and a plurality of upper hole electrode strips (70) are mounted on an upper hole cylinder (116). A plurality of lower countersink electrode strips (68) are coupled to a lower countersink cylinder (124) and a plurality of upper countersink electrode strips (66) are coupled to an upper countersink cylinder (132). A dielectric layer (64) covers a plurality of measuring electrode tips (67, 69, 71 and 73) and an outer surface (150) of the hole and countersink portions (76 and 74). A grounding electrode (158) is mounted on the upper hole cylinder ( 116).

Abstract: A scanning tunnel microscope includes a piezo-actuator movable in a direction Z perpendicular to the surface of a sample and provided with a scanning probe projected downward from the bottom thereof. The scanning probe is moved in the direction Z by the piezo-actuator. The piezo-actuator includes a position measuring probe projected therefrom, parallel to the surface of the sample, from the lower end of one side thereof. A reference sample having concaves formed on a surface thereof at predetermined intervals is fixed to the piezo-actuator. When the scanning probe is moved in the direction Z, the position measuring probe is moved along the reference sample, so that tunnel current having a waveform which reproduces the shape of the concaved surface of the reference sample is detected. Thus, the moving distance of the scanning probe can be obtained from the waveform of tunnel current detected.

Abstract: Analytical equipment, in which liquid substances in sample containers and reagent containers are delivered to reaction cells by a vertically movable probe. The sample containers and the reagent containers are supported on a rotatable metal plate. The metal plate is rotated to place one of the sample containers or reagent containers at a sample or reagent pipetting position. The probe transmits a high-frequency signal to detect a change in electrostatic capacitance between itself and the metal plate at a time the probe is put in contact with a liquid substance in the sample or reagent container. A spline shaft for moving the probe in a vertical direction has a detection plate, and a control signal is generated when the detection plate reaches a predetermined position. The generation of the high-frequency signal is stopped when the probe begins to make a descending motion until the control signal is generated, to reduce the adverse effect of disturbing waves on various parts.

Abstract: A linear capacitance displacement transducer for measuring absolute displacement is formed from a coaxial variable capacitor and a precision capacitance measuring electronic circuit. The plates of the coaxial capacitor are attached to the members of an assembly whose displacement relative to one another is to be determined. Linear displacement of the members causes a linear displacement between the capacitor plates which is reflected in a linear capacitance change. A capacitor controlled oscillator utilizes the coaxial variable capacitor at its input. The capacitor controlled oscillator whose period of oscillation is been determined by the capacitance and locked in phase with changes of capacitance is utilized as a precision measure of capacitance. The period of the square wave output of the oscillator is a linear function of the capacitance of the variable capacitor at any time. The transducer may be adapted to determine the absolute position of a piston rod in a hydraulic cylinder.

Abstract: A capacitance sensor for measuring changes in thickness of a dielectric film, such as plastic film, passed through the sensor, having an upper and lower housing projecting from a back plate, the lower housing having an upper electrode surface and the upper housing having an insulator aligned with the electrode surface; the insulator having an electrode conneced to an electrical conductor; the materials for constructing the two housings, the electrode and the insulator all having a coefficient of linear temperature expansion of less than 1.times.10.sup.-6 per degree Centigrade.

Abstract: A fringe field, capacitive distance sensor for measuring the distance between a probe and the surface of the conductive body. The sensor comprises a conductive plate element mounted by the probe, the thickness of the plate element being substantially less than the height and width of the plate element. The plate element is positioned adjacent to and normal to the body surface, and the fringe field capacitance between the plate element and the body is measured, to thereby determine the distance between the probe and the body surface. The probe may be in contact with and scanned across the body surface, to provide surface profile measurements. A probe including a plurality of plate elements may be positioned inside an opening such as a hole, to measure the geometry of the hole. By maintaining the hole probe adjacent one electrode in contact with the hole wall, both profile and geometry measurements may be made. A noncontacting probe including one or more plate elements may be used to measure surface topography.

Abstract: A device and method for capacitive measurement and control of the fly height of a recording slider. A recording slider is vertically spaced from a rotating disk surface by an "air bearing". The disk has a first electrically conductive pattern at its surface. The first pattern has an edge with a length extending, for example, radially. The recording slider has one or more electrically conductive rails extending transverse to the radial pattern on the rotating disk. As the disk rotates, the edge of the pattern on the disk scans across the rail of the slider. By measuring the electrical capacitance between the slider and the pattern on the disk, and by processing the electrical capacitance measurement signal, a vertical spacing signal proportional to the vertical spacing between the disk and the slider can be obtained.