Abstract: A sensing system locates an object by sensing the object's effect on electric fields. The object's effect on the mutual capacitance of electrode pairs varies according to the distance between the object and the electrodes. A single electrode pair can sense the distance from the object to the electrodes. Multiple electrode pairs can more precisely locate the object in one or more dimensions.

Abstract: A capacitive technique for measuring the thickness of non-conductive, flexible sheet material consists of placing the sheet material over the gap between a pair of coaxial electrodes, the electrodes defining a sensor surface, and keeping the sheet material spaced from the sensor surface by establishing a layer of gas therebetween.

Abstract: A capacitive measuring device with a measuring electrode (3) arranged some distance from a counter-electrode (8), a dielectric material for analysis is arranged between the electrodes (3, 8), and a measuring current (IC) is supplied to the measuring electrode (3) and the capacitance-dependent capacitor voltage (UC) is measured and evaluated.

Abstract: Disclosed is a system that determines whether input and output pins of semiconductor components are present and properly soldered to a circuit assembly. The system includes an oscillator which is connected to a probe that is brought into contact with a circuit assembly wiring trace soldered to the pin being tested. A conductive electrode is placed on top of the component and connected to a capacitance measuring circuit. The oscillator signal is capacitively coupled through the integrated circuit package to the pin being tested, so if capacitance is measured by the capacitance measuring device, the pin is connected to the circuit assembly. An amplifier may be connected to the conductive electrode to amplify the signal, and a segmented probe may be used to isolate individual pins. The probe may be shielded, and unused pins may be grounded.

Abstract: A differential capacitive moisture sensor, relying for its operation on the time-varying couplings in two moisture-sensing regions to provide indication of presence of moisture, with selectivity of sensing surface provided by a shielding electrode, and with temperature information provided by a simultaneously-fabricated resistive temperature sensor. Various electrode connections and sensor electronics may be used.

Abstract: In a wetness sensor for a window of a motor vehicle, a heating resistor arranged in the window and powered by DC current can be connected to a measuring device for measuring an AC impedance of the heating resistor, in particular the capacitive portion thereof. The impedance varies with the amount of wetness and, thereby, serves as a measure of the wetness. A capacitor is used to bring the sensor near resonance for improved sensitivity.

Abstract: Method and apparatus are described for obtaining information about the real and imaginary parts of permittivity in dielectric materials and relating this information to other properties of the materials.

Abstract: A conductive strip detector comprises a capacitor defined by an elongate, electrically conductive element (5) and a laterally spaced, electrically conductive member (1). Monitoring circuitry (15,16) monitors changes in the capacitance of the capacitor when an electrically conductive strip substantially parallel with the element is passed by the capacitor and indicates when a change in capacitance is due to the presence of an electrically conductive strip.

Abstract: Apparatus for inspecting non-round annular containers includes elongated capacitive sensors, cooperating oscillators, which convert the sensor signal to a voltage corresponding thereto, and an electronic processor which receives the voltage and determines thickness. A displaceable electromechanical member is operatively associated with the sensor and emits an electrical signal corresponding to the degree of displacement of the sensor by a container being inspected. The electronic processor corrects the thickness determination by an adjustment of container diameter at the specific location where thickness is being monitored in order to compensate for container diameter variations due to the non-round characteristic of the container. In a preferred embodiment, linkage members secured to the rear of the sensor at a plurality of locations cooperate with a single displaceable element which converts the mechanical displacement of the sensor into a corresponding electrical signal.

Abstract: An apparatus and method for processing materials by sensing roller, in which the sensing roller has a plurality of conductive rings (electrodes) separated by rings of dielectric material. Sensing capacitances or impedances between the electrodes provides information on thicknesses of the materials being processed, location of wires therein, and other like characteristics of the materials.

Abstract: A solid-state fringe effect capacitive proximity sensor is described which lends itself to use for surface mounting and other space constrained applications. The sensor comprises an insulating substrate having a plurality of sensing electrodes formed thereon and without any screen elements therebetween. The electrodes are adapted to measure the proximity distance of a target object (conductive or non-conductive) by means of the fringe capacitance effect created between the electrodes. Capacitance measurement processing circuitry is electrically connected to the plurality of sensory electrodes.

Abstract: A capacity type proximity sensor comprised of a capacitance type sensor, a capacitance type reference, and two independent and mutually opposing driven shields respectively adjacent the sensor and reference and which are coupled in an electrical bridge circuit configuration and driven by a single frequency crystal controlled oscillator. The bridge circuit additionally includes a pair of fixed electrical impedance elements which form adjacent arms of the bridge and which comprise either a pair of precision resistances or capacitors. Detection of bridge unbalance provides an indication of the mutual proximity between an object and the sensor. Drift compensation is also utilized to improve performance and thus increase sensor range and sensitivity.

Abstract: Method and apparatus are described for obtaining information about the real and imaginary parts of permittivity in dielectric materials and relating this information to other properties of the materials.

Abstract: A system and a method is provided for imaging desired surfaces of a workpiece. A sensor having first and second sensing electrodes which are electrically isolated from the workpiece is positioned above and in proximity to the desired surfaces of the workpiece. An electric field is developed between the first and second sensing electrodes of the sensor in response to input signals being applied thereto and capacitance signals are developed which are indicative of any disturbances in the electric field as a result of the workpiece. An image signal of the workpiece may be developed by processing the capacitance signals. The image signals may provide necessary control information to a machining device for machining the desired surfaces of the workpiece in processes such as deburring or chamfering. Also, the method and system may be used to image dimensions of weld pools on a workpiece and surfaces of glass vials.

Abstract: A water drop sensor comprises a pair of electrodes disposed in association with a portion of a surface of a vehicle window within a wipe pattern and having edges defining an extended insulating gap between the electrodes. The electrodes define a gap which varies in width over the range of diameters of drops to be sensed. The result is that the sensor shows more sensitivity to larger drops than to smaller drops as compared with a similar sensor having a constant gap width. The variation in gap width may be continuous or stepwise over the total range of drop diameters.

Abstract: A capacitive probe for inspecting and measuring the diameter of a bore and thus the amount of wear in the bore formed of an electrically insulated housing containing two levels of conductive plates to measure distance between the plates and the rifling grooves and lands of a bore.

Abstract: A system and a method for imaging desired surfaces of a workpiece. A sensor having first and second sensing electrodes which are electrically isolated from the workpiece is positioned above and in proximity to the desired surfaces of the workpiece. An electric field is developed between the first and second sensing electrodes of the sensor in response to input signals being applied thereto and capacitance signals are developed which are indicative of any disturbances in the electric field as a result of the workpiece. An image signal of the workpiece may be developed by processing the capacitance signals. The image signals may provide necessary control information to a machining device for machining the desired surfaces of the workpiece in processes such as deburring or chamfering. Also, the method and system may be used to image dimensions of weld pools on a workpiece and surfaces of glass vials.

Abstract: A capacitance sensing probe is disclosed for taking measurements of features on a workpiece surface. The probe has two electrodes (E.sub.1, E.sub.2) spaced apart in the direction of movement of the probe with the electrodes being disposed in an attitude normal to the surface. Only the edge of the electrodes are exposed to the surface and an electric circuit (EC) is provided for determining the effect of the surface on the fringe field capacitance between the electrodes. Guard electrodes are used to reduce the stray capacitance being measured. Various embodiments are shown with different numbers and arrangements of electrodes.

Abstract: A preferred embodiment of the invention is an apparatus for measuring the position of a point with respect to at least one axis. The apparatus includes a reference electrode located at the reference point and at least one axial electrode fixed along the at least one axis. The axial electrode has a signal transmission property, such as resistivity, as measured between a first end and a point along the axis, which signal transmission property varies with the location of the point of measurement. The axial electrode is coupled to the reference electrode, typically capacitively. The apparatus also includes means for applying an electric signal to the reference electrode; means for measuring an output electric signal at the first end of the at least one axial electrode; and means for evaluating the relation between the output electric signal and the input electric signal to determine the position of the reference point relative to the axis.

Abstract: A rotatable capacitance sensor preferably constructed of a generally cylindrical body mounted on bearings to a carriage assembly. The body has a number of parallel, spaced apart conductive plates having edges extending through the exterior body surface, and alternate ones of the plates are connected via a bearing to a conductor in one part of the carriage assembly, and the remaining ones of the plates are connected via a bearing to a second conductor in another part of the carriage assembly.

Abstract: Apparatus and methods for measuring the properties of a material by employing a driven electrode, a sensing electrode and a shunting electrode. The shunting electrode is disposed in proximity to the driven and sensing electrodes and functions to increase the sensitivity of electrical measurements made between the driven and sensing electrodes by influencing the coupling of the imposed electric field to the sensing electrode to a degree related to the properties of the material under test.

Abstract: A rotatable capacitance sensor for detecting film thickness of a moving film web, the rotatable sensor having a capacitive element arranged to contact the moving web film, the capacitive element electrically connected to projecting shaft ends of the rotatable sensor, resilient conductors urged against the respective shaft ends, and an electrical shield overlaying the resilient conductors and the rotatable shaft, to electrically isolate shaft wobble from the surrounding housing.

Abstract: A rotatable capacitance sensor preferably constructed of a generally cylindrical body mounted on bearings to a carriage assembly. The body has a number of parallel, spaced apart conductive plates having edges extending through the exterior body surface, and alternate ones of the plates are connected via a bearing to a conductor in one part of the carriage assembly, and the remaining ones of the plates are connected via a bearing to a second conductor in another part of the carriage assembly.

Abstract: A sensor which allows dielectric measurements to be made on a high temperature product such as a molten plastic flowing in a conduit. It comprises a ceramic cylinder with an interdigitated electrode capacitor patterned into the inside wall. Uses of the sensor include continuous determination of copolymer composition and polymer viscosity (molecular weight) in a completely non-obstructive manner.

Abstract: An electric measuring arrangement having at least one measuring sensor and an evaluation circuit which makes possible a continuous measurement of not only the level of a conductive liquid in a container but, also, enables evaluation of as much other physical data relating to the liquid as possible, such as its inclination, the position of a movable body in the liquid, linear or rotational acceleration, and speed. Each measuring sensor is designed as a stray field sensor with two measuring electrodes that are at a specific lateral distance from one another, and the container, together with the liquid placed in it, form a part of the measuring arrangement.

Abstract: A capacitive sensor includes a plurality of individual condenser elements, each of which consist of a first, preferably circular, electrode and a second, preferably surrounding ring-shaped, electrode, which are mounted on one side of a nonconducting support. A common conductor is connected to each of the first electrodes of condenser elements. A signal can be detected separately from each of the condenser elements via conductors connected separately to the individual second electrodes. To increase the sensitivity and to avoid interference, the remote side of the support opposite to the one side is provided with a third additional electrode, which is at ground potential and also acts as a shield for interfering couplings. The sensor is used for measurement of the fuel film thickness in the intake of an internal combustion engine.

Abstract: A three-axis velocity probe system for determining three-axis positional velocities of small particles in fluidized bed systems and similar applications. This system has a sensor head containing four closely-spaced sensing electrodes of small wires that have flat ends to establish a two axis plane, e.g. a X-Y plane. Two of the sensing electrodes are positioned along one of the axes and the other two are along the second axis. These four sensing electrodes are surrounded by a guard electrode, and the outer surface is a ground electrode and support member for the sensing head. The electrodes are excited by, for example, sinusoidal voltage having a peak-to-peak voltage of up to 500 volts at a frequency of 2 MHz. Capacitive currents flowing between the four sensing electrodes and the ground electrode are influenced by the presence and position of a particle passing the sensing head.

Abstract: A capacitive proximity sensing element, backed by a reflector driven at the same voltage as and in phase with the sensor, is used to reflect the field lines away from a grounded robot arm towards an intruding object, thus dramatically increasing the sensor's range and sensitivity.

Abstract: A dielectric constant measurement probe assembly includes a coaxial cable ving a outer electrical conductor and a center electrical conductor extending within the outer conductor and terminating at an end portion which projects beyond an end portion of the outer conductor. An adapter member has a central passage receiving the coaxial cable with the outer conductor of the cable extending through the passage of the adapter member and projecting therefrom. An outer tube has a bore composed of first and second axial sections. The second bore section is smaller in diameter than the first bore section. The adapter member is inserted in the first bore section with the end portion of the coaxial cable outer conductor inserted into the second bore section and making electrical contact therewith such that the outer tube thus constitutes an extension of the outer conductor.

Abstract: A tomographic flow imaging system comprising three or more capacitance electrodes positioned around a pipe through which a flow to be monitored passes. The capacitance between each pair of the electrodes is measured, and an output is derived from the measured capacitances which is representative of the distribution of material within the pipe. A predetermined voltage signal is applied to one electrode at a time, and the electrodes other than said one electrode are connected to sources of equal fixed potential. The capacitance of each pair of electrodes is measured by measuring charge flowing between the said other electrode of the pair and the source of potential to which it is connected.

Abstract: A planar interdigitated dielectric sensor useful for measuring the surface properties of a material is disclosed. The sensor is formed on an insulating substrate. Attached to the surface of the substrate is an excitation electrode and a response electrode disposed in an interdigitated pectinate configuration and a resistance temperature device a (metallic strip). Filling the space between the electrodes and the metallic strip is an insulating material of known dielectric properties. The upper surface of the electrodes and the metallic strip are generally coplanar with respect to the insulating material between the electrodes thus forming a flat upper surface on the sensor. This flat upper surface serves to eliminate air gaps between the sensor surface and sample when analyzing relatively viscous materials.

Abstract: A device and method for the determination of the dielectric characteristics of a material sample. The device includes a probe (3) connected to a coaxial line (2) by a connector (30). The probe comprises a conductive tubular member (78) having a conductive rod (8) coaxial to the tubular member and centered on the latter. An annular member is made of a dielectric material is housed in the tubular member, and is integral with the rod. The annular member/rod assembly is slidably carried in the tubular part (7). A resistive force urges the probe in contact with the material sample (4) so that good contact is ensured with the material sample.

Abstract: Capacitive device to measure changes in liquids, such as changes in the mixing ratio of composite liquids, utilizing capacity measured by an electrode probe. An isolating body is located between the electrodes in the liquid and causes a deviation of the field lines to lower the field strength on the electrodes to avoid measurement disturbances from dirt and air bubbles or other contaminants. Furthermore, circuitry for measuring the capacity independently of any disturbing effects of variable ion concentration in the liquid. This is carried out by separately evaluating the phase of a high-frequency signal on a resonance circuit connected to the electrodes.

Abstract: A parallel plate or single surface dielectric analyzer is disclosed including: a distance sensor for accurately measuring the varying distance between the electrodes, such as a linear voltage differential transformer (LVDT), and apparatus responsive to the distance sensor for positioning the electrodes; a force transducer for measuring the applied force on the sample and apparatus responsive to the force transducer to give a desired force by varying the electrode spacing; disposable electrodes made using thick film technology composed of a ceramic substrate with a conductor adhered to its surface; and a temperature sensor built into one of the electrodes such as a platinum ring adhered to the surface of one of the electrodes and apparatus to measure the resistance across the platinum ring.

Abstract: A planar interdigitated dielectric sensor useful for measuring the surface properties of a material is disclosed. The sensor is formed on an insulating substrate. Attached to the surface of the substrate is an excitation and response electrode disposed in an interdigitated pectinate configuration. Filling the space between the electrodes is an insulating material of known dielectric properties. The upper surface of the electrodes are generally coplanar with respect to the insulating material between the electrodes thus forming a flat upper surface on the sensor. This flat upper surface serves to eliminate air gaps between the sensor surface and sample when analyzing relatively viscous materials.

Abstract: A capacitance gauge system is described for determining the thickness of thin-film non-conducting material (i.e. polyethylene, vinyl, etc.). An elongated capacitance sensing head is applied to one side of the material being measured thereby disturbing the electric field produced by the head. Internal circuitry monitors the effect of the material under test and produces an output proportional to the variation in the material's thickness. A new method of resolving capacitance changes results in the ability to resolve capacitance changes on the order of 5.times.10.sup.-17 Farads in a linear manner with the benefits of simplicity, excellent stability, low power requirement, and small physical size. These factors allow said apparatus to be incorporated into a small hand-held unit. Because of this advancement in portability, accurate measurements can be made more quickly and conveniently than previously possible.

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 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 protection device for a waterbed protects the water bladder and water heater from damage due to overheating when a dangerous condition, such as an insufficient level of water within the bladder or an element of the waterbed surroundings interposed between the bladder and the water heater, arises. The protection device employs a detector in the form of two capacitance plates placed adjacent to the water bladder and connected to a circuit which is operative to prevent power from being supplied to the water heater upon detection of a dangerous condition. The capacitance of the detector plates varies with the level of the water within the bladder and with the presence of a surrounding element between the bladder and heater.

Abstract: A device for detecting objects behind a wall or like surface has a multiplicity of capacitor plates at spaced intervals and a circuit for sensing alterations in the dielectric constant of a region of the surface being inspected and adjacent to each of the capacitor plates. A multiplicity of quantitative display elements are arranged at intervals in a visual display, and each display element provides a quantitative value representative of the strength of the signal generated by the associated capacitor plate. Thus, the images in the display elements will increase and decrease to reflect the quantitative signals and effectively image the object being detected.

Abstract: A method and apparatus for processing and analyzing blood serum includes a capacitive sensing unit for receiving centrifuged test tubes and generating output signals indicative of the boundary position between the separator gel and the blood serum in the tubes, and a computer connected to the sensing unit to receive and analyze the output signals of the capacitive sensing unit. An aspirator/dispenser needle and retainer probe unit is positioned above the sensing unit and is capable of lowering a needle; under the control of the computer, to puncture the stopper of a test tube and then withdraw blood serum. The retainer probe prevents the withdrawal or loosening of the tube stopper upon withdrawal of the needle from the tube. A color sensor inspects the aspirated sample and determines whether it is suitable for analysis.

Abstract: A capacitance sensor for measuring thickness variations in film materials, having a sensor mounted in a housing plate slot, with an air gap between the sensor and the housing plate, the sensor being affixed to an insulator support plate, the insulator support plate being affixed to the housing plate, with a bottom plate affixed against the lower side of the housing plate, having enlarged openings for permitting the passage of a conductor to the sensor; all of the conductor and insulator materials having a coefficient of linear temperature expansion of less than 1.times.10.sup.-6 per degree centrigrade, the insulator materials having virtually no dialectic variation with temperature.

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: This invention relates to a method of annoucing a low level of the remaining liquid in a dropper. According to the present invention, two electrodes are attached to the outer surface of a dropper, and a pulse of a stable level is applied to one of these electrodes. The remaining quantity of the liquid in the dropper can be detected automatically with ease by utilizing the variations of the electrostatic capacity occurring between these two electrodes. An annunciator is activated when it receives a signal representative of a low level of the liquid in the dropper, to inform a nurse of the necessity of replacing the dropper.

Abstract: A device for detecting loose ends in tobacco articles such as cigarettes comprises a stationary cam for positioning the articles prior to reaching a flat sensor surface. A pair of concentric electrodes are arranged on the sensor surface for generating an electric field. Cigarettes are moved through the field so as to create a field disturbance. Deviations from a predetermined field disturbance indicate that a cigarette is defective. A piece of thin glass, of about 5.5 mils, covers the sensor surface and is adhered thereto to protect against wear. Compared to surface protecting members previously used, the glass member significantly extends the wear life of the sensor, improves the sensitivity of the device, improves detection accuracy, and eliminates the need for daily readjustment of the field.