Abstract: A liquid level detecting system which utilizes audio frequency with components having sizes and values usually associated with RF frequencies, thereby providing the reliability and low cost of audio components with the small size typically associated with RF systems. A conductive element is mounted within a container, the conductive element is provided with an insulative coating. A large change in capacitance and capacitance reactance is produced when the insulated conductive element is immersed in a conductive liquid. The change in output of the audio oscillator, passed through the low pass network, which includes the capacitance of the conductive element is fed to an active detector. In one application, the detector is utilized to sense the level of water in a fuel/water separator and, in a second application, a pair of liquid level detectors are utilized to control the operation of a bilge pump.

Abstract: An apparatus for measuring distance between two interfaces comprises a first electrically conductive planar member defining the first of the two interfaces, a second electrically conductive planar member defining the second of the two interfaces, an alternating electrical signal generator supplying an input alternating electrical signal to the first electrically conductive planar member through a first electrical conductor having a high value of ohmic resistance, and a phase difference measuring device measuring a phase angle difference between a first output alternating electrical signal taken off from one extremity of the second electrically conductive planar member through a second electrical conductor having a high value of ohmic resistance and a second output alternating electrical signal taken off from the other extremity of the second electrically conductive planar member or from the alternating electrical signal generator; wherein the distance between the two interfaces is determined as a function of

Abstract: A capacitance probe is used by a coordinate measuring machine or machine tool to determine distances from the probe to the workpiece surface at various points over the surface. The probe is calibrated by moving it along a line, which is skewed to the surface. During this movement, a plurality of values of the capacitance and the corresponding values of the actual distance moved along the line are recorded. A datum value for the movement along the skewed line is also determined, which corresponds to a position at which the probe would touch the surface. The probe is calibrated without needing separate independent measurements of the distance from the probe to the surface. The workpiece surface is scanned using the thus-calibrate probe, in which different calibration values are used at different points on the surface, in order to account for the local shape of the surface.

Abstract: A capacitor having two substantially parallel conductive faces is acoustically coupled to a conductive sample end such that the sample face is one end of the capacitor. A non-contacting dielectric may serve as a spacer between the two conductive plates. The formed capacitor is connected to an LC oscillator circuit such as a Hartley oscillator circuit producing an output frequency which is a function of the capacitor spacing. This capacitance oscillates as the sample end coating is oscillated by an acoustic wave generated in the sample by a transmitting transducer. The electrical output can serve as an absolute indicator of acoustic wave displacement.

Abstract: The capacitance sensor (1) comprises a linear or curvilinear array of electrodes (10) connected to means generating on these electrodes (10) a spatially periodic electric potential pattern shifting by increments along said array. Electrodes (10) are disconnected in turn to act as momentarily receiving electrodes (10R), also according to a spatially periodic pattern, shifting by the same increments. Both patterns shift alternately, i.e. the shifts of one pattern taking place between the shifts of the other. A linear or curvilinear scale (2), with a periodic pattern of electrodes (20) or dielectric or conducting relief, facing the sensor, will thus create a periodic fluctuation of the signal coupled on the momentarily receiving electrodes. The relative position between scale (2) and sensor (1) may then be accurately determined by evaluating the phase, after demodulation, of said signal.

Abstract: Page sensor apparatus for producing a signal related to a thickness of a sheet of paper may comprise a base plate and a foot plate positioned in opposed relation. The base and foot plates are arranged to allow the paper to pass therebetween, so that the base and foot plates become separated by a distance substantially equal to the thickness of the sheet of paper. Capacitance sensing apparatus connected to the base plate and the foot plate senses changes in the electrical capacitance of the base and foot plates and generates an output signal related thereto, the output signal being related to the plate separation, thus paper thickness.

Abstract: A level switch includes an operational amplifier, provided with positive and negative feedback, and a sensor, together forming an astable multivibrator. The oscillation onset and frequency of the multivibrator depend on the surface level of controlled material. The sensor includes a dielectric body on which, starting from its fastening end, a grounded opposite electrode and a screening electrode, connected to the amplifier output, are mounted. A ring plate connected to the inverting amplifier input is incorporated coaxially in the dielectric body. The level switch need not be adjusted when the controlled material is changed, although materials may have quite different electrical properties and may stick to the sensor.

Abstract: A capacitive sensor has a pair of plate-shaped electrodes (4) spaced apart from one another and defining a measurement slot (3) therebetween. Guides (5) mask out edge zones of the measurement slot (3) and reduce its width. These guides (5) are formed as the two legs of an elongated U-shaped guiding part (7) which can be inserted into the measurement slot (3) and can be fixed in the latter.

Abstract: Quantitative dopant profile measurements are performed on a nanometer scale by using a scanning capacitance microsope. A nanometer scale tip of the microscope is positioned at a semiconductor surface, and local capacitance change is measured as a function of sample bias. The method incorporates a feedback system and procedure in which the magnitude of the AC bias voltage applied to the sample is adjusted to maintain a constant capacitance change as the tip is scanned across the sample surface. A one dimensional model is used to extract dopant density profiles from the measurements made by the scanning capacitance microscope.

Abstract: A capaciflector sensor system scanned in frequency is used to detect the permittivity of the material of an object being sensed. A capaciflector sensor element, coupled to current-measuring voltage follower circuitry, is driven by a frequency swept oscillator and generates an output which corresponds to capacity as a function of the input frequency. This swept frequency information is fed into apparatus e.g. a digital computer for comparing the shape of the capacitance vs. frequency curve against characteristic capacitor vs. frequency curves for a variety of different materials which are stored, for example, in a digital memory of the computer or a database. Using a technique of pattern matching, a determination is made as to the identification of the material. Also, when desirable, the distance between the sensor and the object can be determined.

Abstract: An apparatus and method for center finding and physical proximity measurement, the apparatus including a reactance controlled signal source for producing a measurement signal having a measurement signal frequency dependent upon reactance and a probe tip connected to the signal source. The probe tip is operable to receive the measurement signal while presenting a measurement reactance to the signal source, the measurement reactance being due to coupling of the probe tip with a workpiece adjacent the probe tip and the measurement reactance varying in accordance with the physical proximity of the probe tip to the workpiece. The measurement reactance causes the signal source to vary the measurement signal frequency according to the proximity of the probe tip to the workpiece. The measurement signal frequency is sufficiently high to enable the measurement signal to be radiated by the probe tip for reception by a remote receiver.

Abstract: A stylus probe with both a contact sensing and a capacitive proximity sensing capability provided by positioning a capacitive sensor means (10) on the tip-end of a grounded, thin conductive stainless steel tube (12) so that the capacitive sensor means (10) is electrically insulated from the grounded tube, and a conductive lead wire (16), conductively attached to the capacitive sensor means (10), extends through the tube (12) with an electrically insulative material (18) dispersed between the tube (12) and the lead wire (16) to electrically insulate and space the lead wire (16) from the tube (12). The connecting-end of the tube (12) has an elastomer material (20) and (22) placed in an annular fashion and in direct contact with a mounting means and the tube (12) so as to dampen vibrations of the tube (12) caused by probe deflection. The stylus probe further comprises a tubular member with a length:width ratio of from about 40:1 to about 300:1 to give up to a 45.degree.

Abstract: A method of determining the best position for an inner member relative to an outer member within a rotary machine requires the inner and outer members to be rotated relative to one another. The spacing between the inner and outer members at at least one location along the length of the rotary machine is detected generally continuously over at least one complete revolution. The detected spacing is then processed to determine the best position for the inner member relative to the outer member. An apparatus for carrying out the method is also disclosed.

Abstract: A device for dynamic measurement of the clearance between the tips of rotating blades and the stator of a rotary machine comprises a capacitive sensor polarized by a direct voltage and conditioned by a continuously polarized load amplifier having a high-pass filter structure, preferably of the second order. The construction of the sensor and of the cable connecting it to the conditioning device is coaxial. The calibration of the measuring chain can be performed theoretically, without having recourse to any testing.

Abstract: A signal processing arrangement for absolute-value sensors in which, within the periodic structure (3) a measurement surface which is divided into a plurality of measurement sections lies opposite at least one probe, each measurement section representing a position marking. Inputs (E.sub.n) of the periodic sensor structure (3) are cyclically connected to a signal source (1) via a switch input group (2), and outputs (O.sub.n) of the periodic structure (3) are connected to an evaluation circuit. In order to convert the geometrical value into an absolute electrical image signal, at least one probe in combination with, in each case, one measurement section forms at least one switch unit for each measurement position (X.sub.i). Between the outputs (O.sub.n) of the periodic structure (3) and the evaluation circuit (5), a cyclically switching output switch group (4) is arranged, and the switch units (X.sub.

Abstract: A sensor system is disclosed for the contactless measuring of the distance between a sensor body and an object. The sensor body contains an identification resistor, the resistance value of which can be interrogated by a control unit which is connected to the sensor body and which is located outside the sensor body. The interrogation makes it possible to determine whether the electrical connection between the control unit and the sensor body exists or is interrupted. If it is interrupted, this can be detected by the control unit in an unambiguous manner due to the missing connection to the identification resistor, and the control unit can generate an alarm signal in order to avoid faulty positioning of the sensor body relative to the object.

Abstract: An apparatus for detecting the level of material in a container. The apparatus comprises a power source and a first electrode, positioned adjacent the container, electrically connected to the power source. The apparatus further comprises a second electrode. The second electrode is spaced from the first electrode and positioned adjacent the container. The apparatus further comprises an electrical amplifier which is electrically connected to the second electrode. The amplifier amplifies a current induced in the second electrode and generates a voltage signal. The amplifier is adapted to maintain the second electrode at a virtual ground to minimize environmental impedance effects. The apparatus further comprises a rectifier, electrically connected to the amplifier, for rectifying the voltage signal and a comparator, electrically connected to the rectifier, for comparing the voltage signal to a predetermined voltage signal corresponding to the container being full with material.

Abstract: A bridge-type capacitance transducer comprising four active components is disclosed. The symmetry of this transducer is maintained in the presence of capacitance change induced by motion. Consequently, there is greater immunity to extraneous stray capacitances, thus greater sensitivity and range of linearity. Sensitivity is further increased by means of synchronous detection at the output.

Abstract: A capacitive measuring device or apparatus; in particular, a length-measuring apparatus, which incorporates a scale portion and a scanning unit which is movable relative to the former and which supports transmitting electrodes and at least one receiving electrode. Herein, a transmission circuit applies transmitting signals at a basic frequency to the transmitting electrodes, and with the receiving electrode being connected to a reception circuit, to the output side of which there is connected an evaluating circuit for the receiving signals. The transmitting signals are applied to the transmitting electrodes through a pulse width modulator and a synchronous modulator and the receiving signal is conducted through a demodulator.

Abstract: A capacitance-type measuring device for absolute measurement of positions is disclosed, which comprises a displacement sensor having a fixed element and a movable element, the movable element being capacitance-coupled to the fixed element and relatively movable against the fixed element, the displacement sensor being adapted to output signals corresponding to relative positions of the movable element against the fixed element, a signal processing circuit for processing the output signals of the displacement sensor and outputting an absolute measurement value corresponding to displacement of the movable element against the fixed element, a control circuit for controlling the operations of the displacement sensor and the signal processing circuit, and a power supply for supplying electric power to the displacement sensor, the signal processing circuit, and the control circuit, wherein the control circuit activates the signal processing circuit at a suitable interval so as to perform an intermittent measurement

Abstract: A stylus assembly in which a stylus is mounted in a housing for movement relative thereto. An electrical circuit is provided for sensing contact of the stylus with a writing surface and measuring the pressure exerted on the surface by the stylus.

Abstract: Electrostatic imaging apparatus comprises a plurality of electrostatic radiators and a signal generator for driving the radiators to produce an electrostatic field having characteristics modifiable by the presence of an object within the field. The field characteristics are detected and processed to produce output signals representative of a surface profile of the object.

Abstract: A method and apparatus involving the use of a thickness measurement probe having a predetermined resolution to measure the thickness of a wafer over a two-dimensional area of the wafer, the method including sampling the measured thickness of the wafer with the probe to generate an image of the two-dimensional area of the wafer, the image being a two-dimensional array of measurements, each measurement representing a measurement of the thickness of a different region of the two-dimensional area, the two-dimensional array of measurements being represented by a measured column tensor; and left multiplying the measured column tensor by a reconstruction tensor T to obtain an estimate of a desired measurement column tensor, where the reconstruction tensor T is equal to R.sub.dm R.sub.mm.sup.-1, R.sub.dm being a cross-covariance tensor computed for d, a desired measurement column tensor, and m, the measured column tensor, and R.sub.

Abstract: A velocity sensor for detecting velocity even in a low velocity range has a velocity detecting element including a movable micromember, a deviation amount detecting device, a holding device and a velocity signal calculating device. The movable micromember is rotatably supported around a center of gravity for generating a frictional force or a dynamical pressure that is proportional to a velocity of a fluid. The deviation amount detecting device detects a deviation amount around the center of gravity of the movable micromember to generate an output voltage, which is proportional to the detected deviation amount. The holding device provides a holding force, which is proportional to the output voltage of the deviation amount detecting device, to the movable micromember and holds the movable micromember to a position around the center of gravity. The velocity signal calculating device calculates a velocity signal from the output of the deviation amount detecting device.

Abstract: A capacitive position sensor has a scale (10), having hollow or raised topographical features, and a cursor (20) having an electrode array comprising at least two transmitting electrodes (21a, 21b) and at least one receiving electrode (21c) separated by shielding electrodes (21g). The coupling capacitances (Cac, Cbc) between transmitting and receiving cursor (20) electrodes are modified as a function of the position (x) of the scale topographic feature (11) relative to the cursor, the evaluation of the variation of the signals picked up by the receiving electrode permitting a precise measurement of the relative displacement between scale and cursor.

Abstract: A method and apparatus for monitoring an electrical property of a conductive coating on an optical fiber, the method comprising capacitively coupling at least one alternating electrical signal into and out of the conductive coating and measuring an electrical property of the coating carrying the alternating electrical signal. The apparatus comprises generating means for generating an alternating electrical signal; capacitive coupling means for capacitively coupling the alternating electrical signal into and out of the conductive coating, the capacitive coupling means being electrically connected to the generating means; and measuring means for measuring an electrical property of the conductive coating carrying the alternating electrical signal, the measuring means being electrically connected to the capacitive coupling means. A method of manufacturing coated optical fiber which incorporates the method of monitoring an electrical property of a conductive coating is also disclosed.

Abstract: A non-intrusive means and method are disclosed for monitoring the interelectrode gap in a reaction chamber containing a pair of variably spaced, nominally parallel reaction-sustaining electrodes. An example is given in which the chamber is a plasma enhanced chemical vapor deposition chamber. The electrodes are treated as a parallel plate capacitor in order to measure the gap therebetween as well as the parallelism of the electrodes without requiring that the chamber be opened. A calibration curve is prepared by ascertaining known values of gaps by use of spacer gauges and then measuring and storing the corresponding values of the gaps and the capacitances. Once the calibration curve is established and stored, the spacing between the electrodes can be checked from time to time, as needed, without opening the chamber. It is only necessary to measure the capacitance existing and then refer the measured value to the stored values to read out the corresponding gap value.

Abstract: Apparatus for measuring the distance between a surface of a workpiece and a predetermined location of the type which measures the capacitance between the predetermined location and the workpiece surface and determines the distance corresponding to the measured capacitance. The apparatus includes a probe disposed at said predetermined location, the probe may be selectively excited to a known electric potential. A support assembly for supporting the workpiece is mounted on the apparatus for rotation relative to the probe. The support assembly is constructed to support the workpiece for rotation and to maintain the workpiece at a substantially constant electric potential. A grounding mechanism for grounding the support assembly includes a fixed grounding member and a liquid ground contact which engages the support assembly for maintaining electrical contact between the support assembly and the fixed grounding member as the support assembly rotates relative to the fixed grounding member.

Abstract: A capacitive type proximity sensor having improved range and sensitivity between a surface and an intruding object in the vicinity of the surface having a voltage source, a number of outer electrical conductors on the surface with each forming one electrode of a number of sensor capacitors, the other electrode for each sensor capacitor being the object. The outer conductors are made from thin sheets of conductive material covered with insulation. An intermediate electrical conductor is located between the outer conductors and the surface and is of a size larger than the outer conductors to act as a shield for reducing the parasitic capacitance between the outer conductors and the surface. The intermediate conductor is also made from a thin sheet of conductive material covered with insulation.

Abstract: An arrangement senses a liquid level by monitoring the peak capacitance formed between a probe and the liquid as the probe approaches or departs from the liquid. In an automated system, a computer controls the position of a pipette probe for aspirating or dispensing liquid in the vessel. The charge developed via the capacitance on the probe is coupled to a capacitive sensor circuit which provides a peak detector with an amplified signal representing the peak capacitance between the probe and the liquid. This amplified signal is detected by a peak-capacitance discrimination circuit, the output of which is monitored by the computer for determining the precise position of the probe with respect to the liquid surface level. Other aspects of the present invention include a negative-static elimination circuit coupled to the output of a detector latch and a positive-static elimination circuit coupled to the input of the detector latch.

Abstract: A cable length indicating arrangement which utilizes the capacitance of a two wire cable (10) to determine its length. The arrangement includes an oscillator stage (14) having a frequency setting capacitor (16) across which the cable is connected. The frequency of oscillation is converted into a voltage which is provided as the input to a comparator network (70, 72, 74, 76, 78, 80) which compares this voltage against voltages derived from a voltage divider network (96, 98, 100, 102, 104, 106, 108). The comparator network includes a "ladder" of comparators each having their non-inverting inputs coupled to receive the frequency dependent voltage and their inverting inputs each connected to a respective point in a resistive divider string. The outputs of the comparators are connected to respective light emitting diodes (82, 84, 86, 88, 90, 92).

Abstract: An acoustic microscope assembly for atomic level inspection of a target object includes a cantilever arm with a sharp tip on its lower surface and a zinc oxide piezoelectric thin film on its upper surface. High frequency excitation signals, having a frequency of at least 50 Megahertz, are applied to the piezoelectric thin film so as to generate high frequency acoustic signals that are transmitted through the sharp tip so as to impact on a target object. The assembly can either receive acoustic signals reflected by the target object, or it can receive acoustic signals that have propagated through the target object. One method of using this assembly is to apply a continuous wave signal to the piezoelectric thin film while scanning the target object, and measuring characteristics of the target object at various positions thereof by measuring the resonant frequency of the transmitted high frequency acoustic signals.

Abstract: A non-contact, omni-directional capacitive probe for use in dimensional gauging includes an electrically conductive spherical sensing tip that forms a capacitor with a workpiece, the capacitance of the capacitor being indicative of the distance between the spherical sensing tip and the workpiece.

Abstract: A capacitive position sensor has a scale (10), having hollow or raised topographical features, and a cursor (20) having an electrode array comprising at least two transmitting electrodes (21a, 21b) and at least one receiving electrode (21c) separated by shielding electrodes (21g). The coupling capacitances (Cac, Cbc) between transmitting and receiving cursor (20) electrodes are modified as a function of the position (x) of the scale topographic feature (11) relative to the cursor, the evaluation of the variation of the signals picked up by the receiving electrode permitting a precise measurement of the relative displacement between scale and cursor.

Abstract: A computer senses a voltage which is representative of wall thickness and defines with the use of a voltage/thickness curve the thickness of that wall portion. To define this curve, a plurality of voltage/thickness points are inputted by a sensor into the computer Each point is defined by sensing and defining the voltage of a wall portion on a calibration standard having a known thickness and defining a calibration thickness corresponding to that voltage using the following equation{((Calibration Standard Diameter in inches -Container Diameter in inches).times.0.2)+1}.times.Calibration Standard Thickness in mils, andequating these calibration thicknesses to the corresponding voltages produced by the sensor when sensing at least two thicknesses of the standard.

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 method and apparatus for measuring chatter marks on a metal workpiece. The method includes first removing gross buckle or curvature in the workpiece by clamping the same in the device having an elongated jaws and in a manner that locates a portion of the workpiece outside of the jaws so that an elongated portion of the workpiece is available for inspection by capacitive sensors. The sensors are located adjacent at least one surface of the elongated portion of the workpiece, the sensor and workpiece forming an electrical capacitor when appropriate potentials are applied to the sensor and workpiece. The sensors are now moved along the surface in the elongated direction of the workpiece to detect chatter marks on the surface.

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 connector is provided, for making electrical connections to a replaceable circuit card. A shielded connection is provided by the connector, maintaining high signal integrity without degradation of S/N ratio by loss of signal or introduction of external noise as a result of connection characteristics without noise across the connection. The circuit card includes only features which are inexpensive to produce, resulting in a low circuit card replacement cost.

Abstract: A method and apparatus for sensing both axial and angular displacements of a collar relative to a shaft. The invention provides transmitting and receiving electrodes on the shaft and coupling electrodes on the collar. Displacements in the axial or angular directions vary the amount of signal conveyed between the electrodes relative to the quantities sought to be measured. An electronic package provides the appropriate signals and allows multiplexing of the data.

Abstract: A tamper-sensing system for an electronic tag 10 which is to be fixed to a surface 11 of an article 12, the tamper-sensing system comprising a capacitor having two non-contacting, capacitively-coupled elements 16, 19. Fixing of the body to the article will establish a precise location of the capacitor elements 16 and 19 relative to each other. When interrogated, the tag will generate a tamper-sensing signal having a value which is a function of the amount of capacity of the capacitor elements. The precise relative location of the capacitor elements cannot be duplicated if the tag is removed and affixed to a surrogate article having a fiducial capacitor element 19 fixed thereto. A very small displacement, in the order of 2-10 microns, of the capacitor elements relative to each other if the tag body is removed and fixed to a surrogate article will result in the tamper-sensing signal having a different, and detectable, value when the tag is interrogated.

Abstract: A displacement measurement apparatus includes a primary electrode, and first and second secondary electrodes which are closely spaced apart and together fully span the primary electrode, the primary and secondary electrodes being movable relative to one another without increasing their transverse separation. A charge pumping means is arranged to supply electric charge to the primary electrode through the first secondary electrode during selected first clock periods, and to withdraw charge from the primary electrode through the second secondary electrode during selected second clock periods. The changeover from one mode of operation to the other is made automatically when the sign of the charge on the primary electrode reverses, so that the charge on the primary electrode is successively increased, and then reduced to a low value.

Abstract: In a measuring device which serves to measure a geometrical variable with the use of a sensor which is fed an alternating measuring current of constant amplitude by a regulated, phase-dependent current source. An alternating supply voltage and an alternating measuring voltage tapped by the sensor via a feedback path of the current source is superimposed in a superimposition stage, which belongs to the current source and downstream of which a reference element for determining the alternating measuring current is connected, to form a total voltage present at the reference element. In order to match a characteristic representing the relationship between the alternating measuring voltage and the geometrical variable to a prescribed characteristic curve, at least one of the alternating voltages fed to the superimposition stage is varied. The variation can concern both the amplitude and the phase.

Abstract: A phase discriminating capacitive sensor array system which provides multiple sensor elements which are maintained at a phase and amplitude based on a frequency reference provided by a single frequency stabilized oscillator. Sensor signals provided by the multiple sensor elements are controlled by multiple phase control units, which correspond to the multiple sensor elements, to adjust the sensor signals from the multiple sensor elements based on the frequency reference. The adjustment made to the sensor signals is indicated by output signals which indicate the proximity of the object. The output signals may also indicate the closing speed of the object based on the rate of change of the adjustment made, and the edges of the object based on a sudden decrease in the adjustment made.

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: The weft break stop motion (1) detects without contact a potential displacement in the feeler (5a) effected by a weft thread moving past by means of a plate-like layered sensor element (2). With the feeler (5a) turned towards the weft thread insertion, the sensor element (2) can be introduced between the drop wires (23) of the reed (18). The weft break stop motion (1) and the sensor element (2) can be variably positioned along the reed (18), depending on the screen of the drop wires (23), and is normally placed directly outside the warp threads according to the loom width.

Abstract: Non-contact measurement of the sharpness of the cutting edge of a slitting or chopping knife is made repeatably placing a capacitance sensor probe symmetrically over the cutting edge at a predetermined distance (nominal offset) from the calibrated sharp edge of the knife and measuring the capacitance to derive a measurement that varies with knife wear (increasing knife edge radius). A novel sensor holder allowing for repeatable precision placement of the sensor.

Abstract: A capacitive sensing circuit and system includes a variable capacitance sensing element as an active element in a circuit to measure changes in capacitance of the sensing element. A switching network in alternate cycles energizes a capacitor to develop a charge which effectively linearizes the sensor's capacitance response. In a push-pull circuit with two active sensing elements, a multi-channel switching network energizes two fixed correction capacitors to provide third or higher order correction, significantly extending the effective scale of the sensor. In a preferred embodiment, a single feedback signal is applied to all capacitors in different switching cycles. Examples include weight and pressure sensing systems.

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.