Abstract: The present invention includes capacitive film thickness measurement devices and measurement systems. The invention also includes machines or instruments using those aspects of the invention. The present invention additionally includes methods and procedures using those devices of the present invention. The present invention discloses a capacitance measurement device and technique useful in determining lubricant film thickness on substrates such as magnetic thin-film rigid disks. Using the present invention, variations in lubricant thickness on the Angstrom scale or less may be measured quickly and nondestructively.

Abstract: A method for determining the position of a rotor with respect to a stator. The method includes generating offset N and Q signals when the rotor moves with respect to the stator and sampling the N and Q signals at a predetermined time interval. A section of a polar plot in which the N and Q signal sample lies is determined and compared to the section of a polar plot in which a previous N and Q signal sample lies. A long range rotor position is calculated by maintaining a count of the change of sections from previous N and Q signal samples. A sub-section rotor position for the N and Q signal sample is calculated and combined with the long range rotor position to create a linear position signal.

Abstract: An occupant detection system for a motor vehicle includes at least two occupant detection devices. A first occupant detection device is, for example, a seat occupancy or weight detection device arranged in the vehicle seat. The second occupant detection device comprises a first electrode arranged in the seat, and a second electrode arranged in the adjoining foot well. An electrical coupling variable is detected, and is used to determine a variable which characterizes an occupant, by means of an electrical field which is applied between the two electrodes.

Abstract: A touch sensor with a sensor surface insulated with respect to ground potential, the sensor surface being connected via a measuring resistor to an a.c. voltage generator, and the voltage across the measuring resistor being used as a difference measuring signal. At least one touch sensor can advantageously be integrated in a sanitary fitting and used to control solenoid valves on water feeds of the fitting. An operating element of the fitting is used as a sensor surface and is connected via a connecting cable to control electronics of the sensor. A method of detecting a touch on an electrically conductive surface, a capacitive touch sensor being used which detects the complex conductance of a human body. The touch detection is carried out by measuring and evaluating a current flow in the direction from the sensor to the person who touches the sensor surface and/or in the direction from the person into the sensor.

Abstract: A sensor assembly for sensing angular position of one object relative to another object. A capacitor is formed between a transmitter capacitor plate having a pair of transmitter electrodes and a receiver capacitor plate having preferably eight receiver electrodes forming four receiver electrode pairs. A dielectric rotor rotates between the plates, the rotor having first and second segments each subtending 67.5 which are mutually separated by a vacancy subtending 45 degrees, and further having a third segment subtending 45 degrees disposed between the first and second segments diametrically opposite the vacancy. An electrical circuit measures net charge induced on each of the receiver electrode pairs, wherein the charges indicate the angular position of said rotor relative to said transmitter and receiver capacitor plates.

Abstract: A distance sensor has a capacitive element in turn having a first plate which is positioned facing a second plate whose distance is to be measured. In the case of fingerprinting, the second plate is defined directly by the skin surface of the finger being printed. The sensor comprises an inverting amplifier, between the input and output of which the capacitive element is connected to form a negative feedback branch. By supplying an electric charge step to the input of the inverting amplifier, a voltage step directly proportional to the distance being measured is obtained at the output.

Abstract: In a first aspect, a method of inspecting objects is provided. The method includes the steps of (1) measuring sheet resistance of a first stack of conducting films deposited on an object, said first stack having a topmost conducting film; (2) depositing a subsequent conducting film on said first stack of conducting films to form a second stack; (3) measuring sheet resistance of said second stack; and (4) calculating sheet resistance of the subsequent conducting film. A thickness of the subsequent conducting film may be determined based on the sheet resistance of the subsequent conducting film. Numerous other aspects are provided.

Abstract: A fingerprint detector having a smooth sensing surface for contact with a fingerprint includes capacitive sensor plates defining an array of sensor cells below the sensing surface and tungsten ESD protection grid lines surrounding each sensor cell. The sensing surface is defined by an alumina layer with the tungsten grid lines embedded therein. The alumina layer provides a sensing surface with improved scratch resistance. The resulting detector is more sensitive in its capacitive sensing due to the relatively high dielectric constant of the alumina layer.

Abstract: The invention relates to a method and a device for measuring and indicating the level of a filler material in a container, said filler material being either electroconductive or nonconductive. A sensor (22) in applied to the wall of the container (20) or is integrated into the same. An alternating voltage is applied to the sensor (22) in order to measure the level, the capacity or the electrical field produced being a measure for the fill level.

Abstract: A non-contact capacitive displacement measurement gage that provides high accuracy displacement measurements of well-connected targets and poorly-connected targets. The capacitive displacement measurement gage includes a capacitive probe, first and second amplifiers, and a signal generator. The capacitive probe includes a sensor electrode, a guard electrode, and a compensating electrode. The signal generator provides a predetermined voltage signal directly to the sensor electrode, to the guard electrode through the first amplifier having unity gain, and to the compensating electrode through the second amplifier having a predetermined transfer function. The second amplifier assures that substantially zero current is driven into the target element by the probe during gage operation, thereby allowing highly accurate displacement measurements of target elements having unknown or poorly controlled impedance.

Abstract: The capacitive coupling of at least two electrodes with an electrically conductive body may be determined when an AC voltage is applied to each of the electrodes and the currents flowing from each of the electrodes are measured. The currents flowing from each of the electrodes are measured n times, when n≧2, while different AC voltages are applied to the electrodes for each of the measurements. The coupling capacitances are calculated in a network analysis using the respective current and voltage values of the n measurements.

Abstract: An angle transducer comprising a first disk, the rotor, with circularly arranged and radially directed receiver electrodes and a second disk, the stator, equipped with circularly arranged and radially directed transmitter electrodes arranged at the same radius as the receiver electrodes and with a fixed separation between the receiver and transmitter electrodes, whereby the disks are arranged coaxially and rotatable relative to each other, and the disks are further separated by a thin air-gap. The transmitter electrodes are each supplied with an alternating voltage with different phases for neighboring electrodes, whereby the number of supply phases, &phgr;, is greater than two, and the separation of the transmitter electrodes=the separation of receiver electrodes/&phgr;.

Abstract: A distance measuring system (1) is provided with a capacitive sensor (7a, 7b), designed in the form of a differential capacitor (18), for which the partial capacitors (C1, C2 have capacitances that depend on the position to be determined. The system also includes a processing device (5) for determining the desired distance that contains, for example, a sigma/delta demodulator. The partial capacitors (C1, C2) are triggered periodically with binary signals, wherein the trigger signals from the one partial capacitor (C1) are transmitted with a phase offset to the signals from the other partial capacitor (C2). The processing device (5) determines which trigger signals must be used for the evaluation. Within time windows that are synchronized with the edges of the trigger signals, a switch unit (22) allows the associated receiving signals to pass through to the processing unit (5) and blanks out all other signals.

Abstract: A vehicle occupant proximity sensor includes a transmitting electrode in a vehicle seat and an array of receiving electrodes mounted in a vehicle headliner above the vehicle seat. The sensor determines the capacitance at each of the receiving electrodes, which varies based upon the proximity of the occupant to each receiving electrode, thus producing an array of proximity information indicating in two dimensions the position of the occupant.

Abstract: A capacitive fingerprint sensor includes a polymeric protective coating defining a sensing surface and having conductive particles suspended therein. The conductive particles act as parallel strings of series capacitors to couple the capacitance the fingerprint-bearing skin of a user's finger applied to the sensing surface to capacitive sensing elements beneath the protective coating. The polymeric material of the coating is durable and scratch resistant. The conductive particles enable use of a protective coating of 10 to 20 microns in thickness while providing a high degree of sensitivity and image resolution.

Abstract: A vehicle occupant proximity sensor includes a transmitting electrode in a vehicle seat and an array of receiving electrodes mounted in the vehicle seat. The sensor determines the capacitance at each of the receiving electrodes, which varies based upon the proximity of the occupant to each receiving electrode, thus producing an array of proximity information indicating in two dimensions the position of the occupant.

Abstract: Error in a process variable measurement due to leakage conductance in an industrial process control transmitter is compensated by identifying capacitance deviations &dgr;CH and &dgr;CL based on leakage conductance for each of the capacitive sensors.

Abstract: A container having an electrically conductive container body. The container body defines a container cavity. A sensor assembly is disposed within said container cavity. The sensor assembly is electrically isolated from the container body, and is configured for sensing a level of material within the container cavity.

Abstract: A system for detecting motion and proximity by determining capacitance between a sensor and an object. The sensor includes sensing surfaces made of a thin film of electrically conductive material mounted on a non-conductive surface. In another embodiment, the sensor is a human body. The sensor senses the capacitance between a sensor's surface and an object in its vicinity and provides the capacitance to a control system that directs machine movement. Because the sensor does not require direct contact or line-of-sight with the object, a machine can be controlled before harm occurs to the object.

Abstract: A capacitance-based position sensor configured to sense relative position of a pair of objects. The sensor includes capacitor circuitry having a capacitor that varies in capacitance with relative position of the pair of objects. A source is coupled to the capacitor circuitry, and is configured to apply a time-varying input to the capacitor circuitry. The capacitor circuitry is configured to yield a time-varying, capacitance-dependent output in response to application of the time-varying input from the source. The sensor further includes an integrator configured to integrate, for a predetermined time period, a received signal that is based upon the time-varying, capacitance-dependent output from the capacitor circuitry. The integration yields an integrator output which is proportional to the value of the capacitance. This output is usable to determine relative position of the objects.

Abstract: The length of an electrical cable is measured from only one of its ends, even though much of the cable may not be visible and its remote end may not be accessible. The ends of a conductor pair are selected to serve as contacts for a test capacitor. A reference capacitor having known capacitance value, and the test capacitor, are alternately inserted into an oscillator circuit while measuring the oscillator frequency. The two oscillator frequencies are compared to provide a ratio, which is then mathematically combined with a number indicative of the capacitance per unit length of the cable so as to produce an output number representing cable length.

Abstract: A method for determining the position of a rotor with respect to a stator. The method includes generating offset N and Q signals when the rotor moves with respect to the stator and sampling the N and Q signals at a predetermined time interval. A section of a polar plot in which the N and Q signal sample lies is determined and compared to the section of a polar plot in which a previous N and Q signal sample lies. A long range rotor position is calculated by maintaining a count of the change of sections from previous N and Q signal samples. A sub-section rotor position for the N and Q signal sample is calculated and combined with the long range rotor position to create a linear position signal.

Abstract: A system for qualifying and monitoring bearing performance and condition in a rotary servo system. A position error signal is analyzed for signal anomalies that can signify bearing damage. A DC offset ramp is applied to the position error signal to test whether the anomaly is angular position dependent. The anomaly is associated with the corresponding command signal value and range of values to calculate the angular position and range of the apparent bearing damage. The amplitude of the anomaly is measured and associated with a relative degree of bearing damage.

Abstract: The invention comprises a fixed platform (1) and a displaceable platform (2) that are coupled by six tension springs (3) and an elastic spacer member (6). The spacer member forms with each platform, for instance, a ball-and-socket joint, such that the platforms can be displaced in a total of five to six degrees of freedom in respect to each other. The displacement is detected by measurements at the tension springs (3) or at the spacing member (6). This is preferably done by measuring the inductivity of the tension springs (3), thereby making it possible to easily determine the relative position of the platforms.

Abstract: A transmission electrode 10 and a detection electrode 12 are placed in an electrode section of a sensor and are capacity-coupled with a reception electrode placed on an opposed scale. Capacity change between the transmission electrode 10 and the reception electrode caused by displacement is detected with the detection electrode 12. A plurality of signals different in phase are supplied to the transmission electrode 10. The signal lines are wired like a zigzag using an upper layer and a lower layer and the distances between the signal lines and the detection electrode 12 are made substantially equal for making uniform the crosstalk amounts relative to the detection electrode 12.

Abstract: A system and method are disclosed for shielding a capacitive sensor. The system and method drive the shield to the same potential as the sensor electrode being shielded to eliminate sensor interference due to mutual capacitance. An independently created signal is applied to the shield which matches the signal applied to the sensor electrode. Use of the independent driving signal allows the shield to maintain the same potential as the sensor electrode, especially during rapid transition of the sensor electrode's potential.

Abstract: The length of an electrical cable is measured from only one of its ends, even though much of the cable may not be visible and its remote end may not be accessible. The ends of a conductor pair are selected to serve as contacts for a test capacitor. A reference capacitor having known capacitance value, and the test capacitor, are alternately inserted into an oscillator circuit while measuring the oscillator frequency. The two oscillator frequencies are compared to provide a ratio, which is then mathematically combined with a number indicative of the capacitance per unit length of the cable so as to produce an output number representing cable length.

Abstract: Invention relates to a capacitive proximity switch with an electrical bridge circuit for detecting of an electrically conducting face (15) approaching or moving away, wherein the electrically conducting face (15) is part of a capacitor (for example C1) of the bridge circuit, wherein at least one capacitor (C1, C2, C3, C4) and possibly at least one resistor (R9, R10) are disposed in the bridge branches of the bridge circuit as further reactances, and wherein the bridge is subjected to an alternating voltage as a bridge feed voltage (ubr). The proximity switch includes a flat multilayer printed circuit board (10) having at least two electrically insulating layers (13, 14), wherein an electrically conducting intermediate layer (11) as a first face of a capacitor is disposed between the two electrically insulating layers (13, 14).

Abstract: A vehicle occupant proximity sensor includes a transmitting electrode in a vehicle seat and an array of receiving electrodes mounted in a vehicle headliner above the vehicle seat. The sensor determines the capacitance at each of the receiving electrodes, which varies based upon the proximity of the occupant to each receiving electrode, thus producing an array of proximity information indicating in two dimensions the position of the occupant.

Abstract: A device is provided for measuring the weight of a vehicle seat and the weight of a person sitting on the vehicle seat. The device is equipped with a load sensor for converting at least a part of the seat weight to an electric signal, and a deviation/deflection absorbing mechanism which has a pin bracket and a pin and is provided between the seat and the load sensor. The deviation amount that can be absorbed by this absorbing mechanism is a fixed value.

Abstract: A grid of capacitor surfaces is connected to read lines and control lines. The read lines are connected alternately to the output of a feedback operational amplifier and to a collecting capacitor. The capacitances to be measured are charged repeatedly and the charges are collected on the collecting capacitors. Between the charging operations, the potential on the read lines is kept constant through the use of the low-resistance output of the operational amplifier. The use of this method in the case of a fingerprint sensor makes it possible to evaluate all the read lines together.

Abstract: A method for inductively measuring the position of a metal strip is proposed, in which, at least on one side of the strip, a primary coil fed by AC voltage is arranged on one side of a strip edge and a secondary coil is arranged on the other side of the strip edge, which secondary coil measures the voltage which is induced by the primary coil and results from the coupling effect with the primary coil and the metal strip situated in between, in which, as a result of lateral relative movement between the metal strip and the primary and secondary coils, the measurement gradient that can be obtained as a result is determined and compared with a predetermined optimum measurement gradient, whereupon, in the event of a difference, the measurement gradient that has been ascertained is matched electronically to the predetermined optimum measurement gradient and the adapted values then obtained are used for the current strip movement control.

Abstract: A capacitive fingerprint sensor includes a polymeric protective coating defining a sensing surface and having conductive particles suspended therein. The conductive particles act as parallel strings of series capacitors to couple the capacitance the fingerprint-bearing skin of a user's finger applied to the sensing surface to capacitive sensing elements beneath the protective coating. The polymeric material of the coating is durable and scratch resistant. The conductive particles enable use of a protective coating of 10 to 20 microns in thickness while providing a high degree of sensitivity and image resolution.

Abstract: Surface irregularity of a semiconductor device is measured with high accuracy, without being affected by the material properties of a semiconductor film forming the surface. Surface irregularity is evaluated when the semiconductor device is fabricated. This is accomplished using a plate-like element, which has a contact surface brought into contact with the surface of a test specimen. The plate-like element is then moved across the surface of the test specimen by a driving mechanism. The driving mechanism moves either the plate-like element or the test specimen relative to the other. A force caused by the motion is detected, and converted into a parameter equivalent to the friction coefficient between the test specimen and the contact surface. From the friction coefficient, surface irregularity is determined.

Abstract: In one embodiment, a proximity sensor is disclosed. The proximity sensor is adapted for use in a housing, such as an explosion-proof housing, and includes a compressible sensor plate and an interface board. The sensor plate is compressed during assembly of the housing. The proximity sensor interacts with other electrical components within and external to the housing. Furthermore, the proximity sensor may include, or interact with, a display. Components, including the proximity sensor, may be configured for use in a hazardous environment and designed to draw minimal current.

Abstract: A vehicle occupant proximity sensor includes a transmitting electrode in a vehicle seat and an array of receiving electrodes mounted in a vehicle headliner above the vehicle seat. The sensor determines the capacitance at each of the receiving electrodes, which varies based upon the proximity of the occupant to each receiving electrode, thus producing an array of proximity information indicating in two dimensions the position of the occupant.

Abstract: A non-contact measuring method and apparatus for producing a signal representative of a distance between facing surfaces of first and second parts, which are closely spaced apart such as the rotor and stator of an electric rotating machine. The method resides in positioning a sensor on the surface of the first part. The sensor includes first and second parallel, superimposed conductive plates electrically insulated from one another. The second plate is located in between the first plate and the surface of the first part. The first plate is fed with a high frequency signal through a resistance. A high impedance, low input capacity, unitary gain voltage amplifier is fed with the high frequency signal through the resistance. The second plate is fed with an output signal of the amplifier. The output signal of the amplifier is directly proportional to the distance between the two surfaces.

Abstract: A wireless liquid sensing system includes a beverage container and a table top for holding the container. Embedded in the walls and bottom of the container are two electrically conductive plates coupled to a transponder wire coil. A reader radiates an RF signal at a predetermined frequency through a reader antenna. A microprocessor, also coupled to the transponder coil and the two plates, is powered by a rectifier circuit that gains power from then radiated RF signal. The microprocessor amplitude modulates the RF signal in accordance with the amount of liquid in the container. The reader can then detect this modulation with a peak detector to sense the amount of the substance in the container when the transponder antenna is inductively coupled to the reader antenna at the predetermined frequency.

Abstract: A scanning probe detects phase changes of a cantilevered tip proximate to a sample, the oscillations of the cantilevered tip are induced by a lateral bias applied to the sample to quantify the local impedance of the interface normal to the surface of the sample. An ac voltage having a frequency is applied to the sample. The sample is placed at a fixed distance from the cantilevered tip and a phase angle of the cantilevered tip is measured. The position of the cantilevered tip is changed relative to the sample and another phase angle is measured. A phase shift of the deflection of the cantilevered tip is determined based on the phase angles. The impedance of the grain boundary, specifically interface capacitance and resistance, is calculated based on the phase shift and the frequency of the ac voltage. Magnetic properties are measured by applying a dc bias to the tip that cancels electrostatic forces, thereby providing direct measurement of magnetic forces.

Abstract: A sensor for the capacitive measurement of film thicknesses, with a drum (10), which rolls along the film (12) and has at least one measuring capacitor (C1-C4), the plates of which are disposed in the peripheral surface of the drum (10), so that its capacitance is effected by the thickness of the firm, and with a transformer (26), for transmitting the measurement signal from the rotating drum (10) to the stationary part (28), where an oscillator (OSZ1-OSZ4), which is integrated in the drum (10), generates a frequency signal (24), which depends on the capacitance of the measuring capacitor (C1-C4).

Abstract: Both a sensor portion and a signal processing portion are provided on a glass board. The sensor portion is formed by subjecting a conductive layer to the patterning process. A gold coupling layer is provided on the conductive layer and the signal processing portion is formed by the flip chip method on the coupling layer. The sensor portion and the signal processing portion may be formed on the major surface and the rear surface of the glass board and these portions may be coupled by through holes. Since the signal processing portion as well as the sensor portion is formed on the glass board, the wiring distance can be made shorter and the entire size of the sensor can be miniaturized.

Abstract: There is provided a small, high-performance electrostatic capacitance probe device and a displacement measuring circuit using the probe device. The electrostatic capacitance probe device is formed from a processed, stacked substrate with a silicon substrate/insulator/silicon substrate structure. A support substrate (1) is formed through a process of etching the first silicon substrate to remove undesired portions. A probe (2) is formed by etching the second silicon substrate and provided with a proximal electrode portion (2b) secured on the support substrate (1) by means of the insulator (11) and a beam portion (2a) separated from the support substrate (1) by removing the insulator (11) from beneath the beam portion (2a). A pair of detecting electrodes (3, 4) is formed by etching the second silicon substrate, secured on the support substrate (1) by the insulator (1) and located to sandwich a portion of the beam portion (2a) close to the proximal electrode portion (2b).

Abstract: A method for detecting displacements of a micro-electromechanical sensor including a fixed body and a mobile mass, and forming a first sensing capacitor and a second sensing capacitor having a common capacitance at rest. The first and second sensing capacitors being connected to a first input terminal and, respectively, to a first output terminal and to a second output terminal of the sensing circuit. The method includes the steps of closing a first negative-feedback loop, which is formed by the first and second sensing capacitors and by a differential amplifier, feeding an input of the differential amplifier with a staircase sensing voltage through driving capacitors so as to produce variations of an electrical driving quantity which are inversely proportional to the common sensing capacitance, and driving the sensor with the electrical driving quantity.

Abstract: A method and an apparatus for measuring capacitances between electrodes of an ink-jetting head. The apparatus includes a multi-probe having a plurality of probes to contact a plurality of electrode rows as one lump contact, each of the probes contacting one of the electrode rows and a plurality of the probes being divided into a predetermined number of groups. The apparatus further includes a plurality of scanners, each of which corresponds to each of the groups, to sequentially switch contacting-terminals of a plurality of the probes and a plurality of capacitance-measuring devices, each of which corresponds to each of the scanners, to measure capacitances between electrodes in all of the groups in parallel.

Abstract: A capacitance fuel-gauging system has a capacitive probe and a reference capacitor charged in opposite senses from respective dc voltage sources via switches operated in antiphase. Two further switches alternately discharge the capacitors to a 0 volts rail. The outputs of the probe and the reference capacitor are connected to a summing node, which is connected to an amplifier via a pair of switches operated in antiphase to rectify the output. The amplifier connects to a processor, which controls the relative outputs of the voltage sources and provides an output indicating the value of the probe.

Abstract: The subject of the invention is a coating thickness gauge with at least one measuring probe (14) which has at least one sensor (15, 15′) as well as a device for the zero adjustment and/or calibration. The coating thickness device (10) is equipped with means to automatically activate zero adjustment and/or calibration when an interaction especially a contact or a relative movement between a sensor (15, 15′) and a reference plate (11, 11′).

Abstract: A two dimensional array of electrods for sensing the presence or absence of the ridges in a fingerprint through capacitive measurements. Exciting signals are supplied from outside the array which allows the array to be fabricated from metal and insulator layers on non-semiconductor substrates such as glass or plastic using normal deposition and patterning techniques. A top protective layer consisting of hard, rigid material may be provided. The required electronic circuits are preferably located around the periphery of the array.

Abstract: A proximity detector including a reference oscillator and a measurement oscillator, the frequency of which depends on the proximity of an object, particularly a metal object. A detection counter value A, which is controlled by the frequency F of the measurement oscillator, is compared to a set point counter value B to create the output signal. The set point counter value B0, which is determined during the calibration operation, is corrected by a quantity C that depends mainly on the difference of the measured temperature &thgr; compared to the calibration temperature &thgr;0. The proximity detector may find particular application to the detection of ferrous or nonferrous objects by universal or selective, inductive or capacitive detecting elements.

Abstract: An apparatus and method for determining a position and/or orientation of a conductor disposed in a conductive fluid. A plurality of electrodes disposed about the conductor and preferably being in contact with the conductive fluid are used to provide an electrical path between each electrode and the conductor. In one embodiment, resistances between each electrode and conductor are determined through use of a signal processing circuit. In another embodiment, capacitances between each electrode and the conductor are determined using a similar signal processing circuit. Once the resistances or capacitances are determined, the position of the conductor can be determined based on these values in combination with parameters relating to the configuration of the electrodes and conductor, as well as characteristics of the conductive fluid. In one implementation, the invention may be used in free space optical communication systems, whereby the position of the end portion of the fiber optic cable can be determined.

Abstract: A fingerprint detector having a smooth sensor surface for contact with a fingerprint includes capacitive sensor plates defining an array of sensor cells below the sensor surface and tungsten ESD protection grid lines surrounding each sensor cell. The sensor surface is defined by silicon carbide and includes silicon oxide filling cavities in the silicon carbide. The cavities inherently result from processing steps, including removal of the tungsten atop the silicon carbide that is used to define the grid lines. Filling the cavities with oxide and smoothing the surface using chemical mechanical polishing provides a scratch-resistant surface and improves the sensitivity of the capacitive sensor cells.