Showing papers on "Inductive sensor published in 1998"

Position and movement resonant sensor

Abstract: An object sensing system (10) employs a resonant sensor (20) that receives drive energy coupled from an oscillator (12) operating at a frequency equal or close to the resonant frequency of the resonant sensor. The resonant sensor preferably includes an planar winding (60) that maximizes its distributed inductive and capacitive components, which are sensitive to a proximal conductive, nonconductive, magnetic, or nonmagnetic object (22). The resonant sensor is electrically connected in one leg of a voltage divider that produces a changing output signal voltage in response to resonant frequency changes caused by the object in proximity to the resonant sensor. The signal voltage is amplified, filtered, and processed to extract relevant data indicative of the presence, distance, movement, or proximity of the object.

Ultra-wideband impedance sensor

Abstract: The ultra-wideband impedance sensor (UWBZ sensor, or Z-sensor) is implemented in differential and single-ended configurations. The differential UWBZ sensor employs a sub-nanosecond impulse to determine the balance of an impedance bridge. The bridge is configured as a differential sample-and-hold circuit that has a reference impedance side and an unknown impedance side. The unknown impedance side includes a short transmission line whose impedance is a function of the near proximity of objects. The single-ended UWBZ sensor eliminates the reference side of the bridge and is formed of a sample and hold circuit having a transmission line whose impedance is a function of the near proximity of objects. The sensing range of the transmission line is bounded by the two-way travel time of the impulse, thereby eliminating spurious Doppler modes from large distant objects that would occur in a microwave CW impedance bridge. Thus, the UWBZ sensor is a range-gated proximity sensor. The Z-sensor senses the near proximity of various materials such as metal, plastic, wood, petroleum products, and living tissue. It is much like a capacitance sensor, yet it is impervious to moisture. One broad application area is the general replacement of magnetic sensors, particularly where nonferrous materials need to be sensed. Another broad application area is sensing full/empty levels in tanks, vats and silos, e.g., a full/empty switch in water or petroleum tanks.

Sensor system and manufacturing process as well as self-testing process

Abstract: Presented is a sensor system for the detection of thermal radiation, with a substrate ( 15 ) and several sensor elements ( 10 ) on the substrate ( 15 ), in which case at least one self-test device ( 53 ) is provided in order to generate heat which can be used for the heating of one or more sensor elements ( 10 ). The sensor elements ( 10 ) can be heated according to a typical time pattern during the self-testing process. Also presented is an advantageous process for the manufacture of the sensor system as well as an advantageous configuration of the total system, including signal processing.

Sensor device having a magnetic field sensor integrated with an electronic control circuit

Abstract: In a sensor device including a magnetic field sensor which is arranged in stationary fashion and configured as a Hall sensor and is magnetically coupled to at least one stationary magnetic flux conductor which senses a variable magnetic field and delivers it to the Hall sensor, the Hall sensor delivering to an electronic control circuit an electrical signal which depends on the change in the magnetic field, in order to achieve a reduction in the space required for the electronic control circuit and the Hall sensors it is proposed the at least one Hall sensor, combined with at least one element of the electronic control circuit into an application-specific integrated circuit (ASIC), be arranged in an electronic component.

Micromachined inductive sensor having capacitively decoupled coils

Abstract: This micromachined inductive sensor is used to detect, without contact and through the intermediary of a radiated alternating magnetic field, the position and/or the movement of an object capable of modifying this magnetic field and including for this purpose at least one discontinuity. The sensor comprises a planar transmitter coil for transmitting the alternating magnetic field and planar receiver coils located so as to sense a determined portion of said field and the variations of this magnetic portion sensed due to the discontinuity of the object. The coils are disposed on a common substrate and obtained by selective photolithography operations. According to the invention, in the areas of the substrate in which the transmitter coil is contiguous with a receiver coil, there is provided at least one shielding band electrically independent of the coils and connected to a reference potential. The shielding band is formed from a metallization layer deposited on the substrate.

The design of a proximity inductive sensor

Abstract: In this paper we discuss the advantages of flat coil inductive proximity sensors. The coil copper helix may be realized by application of a photoengraving technique to two side-printed boards by a very cheap process. The low thickness allows one to get the coil closer to the target. This fact allows one to attain a higher sensitivity. The coil's low intrinsic capacitance and inductance allow one to work at high frequencies (up to some megahertz). As a consequence the sensor's time constant may decrease to some microseconds. A discussion of the parameters that influence the sensor's performance is reported. Special attention has been given to the coil's shape, the target and the electronic revealing circuit required for promptly functioning and precise devices. The complete analysis of the influences of these parameters on the sensor's performance gives useful suggestions that allow one to obtain a fast response, high sensitivity and high intrinsic insensitivity versus temperature. This is obtained by adopting flat coils, bimetallic (magnetic-non-magnetic) targets and an electrical bridge or frequency-shifting circuit. This provides a substantial improvement in performance with respect to previous solutions.

Metallic profile and coin imaging using an inductive proximity sensor microsystem

Abstract: We have realized metallic profile and coin imaging using a miniaturized inductive proximity sensor. The sensor is a microsystem composed of a 1 mm diameter coil and a new ASIC interface based on the principle of a differential relaxation oscillator. We successfully acquired wellrecognizable images of various coins with different geometrical, electrical and magnetic properties. The integration of such sensor microsystems on a line will open the way to fast and safe coin pattern recognition.

Oil burner motor and refrigeration and air conditioning motor diagnostic apparatus

Abstract: The present invention is an apparatus for monitoring the running time and cycle time of electric motors. The apparatus diagnoses fuel consumption and burner functionality in heating plants by measuring elapsed motor running time. Alternatively, the apparatus diagnoses the running and cycle time of refrigeration and air conditioning motors for the purpose of measuring efficiency and predicting failures. The Apparatus has three major components: an inductive sensor device mechanically attached to the motor; a microprocessor device connected by cable to the inductive sensor device that records time and sensor device data and retransmits it; and the central monitoring device. The microprocessor device is connected by telephone to the central monitoring device. Using historical data of fuel deliveries and consumption and the sensor-supplied running time information, the central monitoring device will predict when the fuel tank needs refilling. The data can be used to indicate a failure has occurred. In addition, the central monitoring device is able to monitor a plurality of sensor devices. This data can be used by a fuel company to schedule and optimize fuel deliveries. When used in refrigeration and air conditioning applications, the apparatus monitors the time the compressor motor is running and the time it is idle. This ratio provides the efficiency of the system and advance notice of potential failures and possible refrigerant loss.

Diagnostic device for recognizing short circuits or line interruptions of an inductive sensor

Abstract: A symmetric voltage divider is connected between the terminals (5, 6) of an inductive sensor (1). The tap (8) of said voltage divider is fed to a reference voltage (Vref) via a resistor (R1). A diagnostic voltage is present on the tap (8). The diagnostic voltage (Vdiag) is first compared with two threshold values (S1, S2) at rest and then sampled in an operating state. The difference (Vss) is calculated from the largest and smallest sample value, said difference being compared with a third threshold value (S3). Short circuits or line interruptions are recognized/displayed from the comparison result.

High-resolution miniaturized inductive proximity sensor: characterization and application for step-motor control

Abstract: A resolution better than 50 nm has been achieved with a new miniaturized inductive proximity sensor. This sensor microsystem is made of a 1 mm diameter coil connected to a new and highly sensitive ASIC based on a differential relaxation oscillator. Lateral as well as axial resolutions have been characterized. A microsystem for step-motor control with an accuracy better than 2 ° is demonstrated. This application is not affected by the temperature behaviour of the sensor.

Method for evaluating an output signal of a rotational sensing device

Abstract: An evaluation method for an output signal of a sensing device for scanning a cyclic movement, consisting of a rotatable pole wheel provided with equidistant teeth and an inductive sensor, permits recognition and display of damage to the pole wheel, in particular defective or missing teeth. Contrary to known evaluation processes, where error monitoring of the output signal is carried out for a relatively short time period comprising few signal cycles of the output signal, an observation of the output signal is effected for a sufficiently long time span in the evaluation process according to the invention, such that within the time span, at least two complete revolutions of the pole wheel are completed. To detect damage to the pole wheel, the sudden changes in the output signal occurring in the course of a complete revolution are recorded and are compared with changes recorded in previous, complete revolutions. If the numbers of changes are in at least approximate agreement, an error signal which can be displayed, for example optically, is produced.

Optical sensor apparatus and signal processing circuit used therein including initialization and measuring modes

Abstract: An optical sensor apparatus capable of accurate measurement without using a filter circuit, and therefore being further capable of pulse driving an LED and thus reducing power consumption, is provided. To achieve such an optical sensor apparatus, when an optical current sensor 10 is not sensing the current to be measured, an optical current sensor signal processing circuit 11 first supplies dc light of a specific intensity to the optical current sensor 10, and then adjusts the intensity of the light so that the intensity of light returned from the optical current sensor 10 to the signal processing circuit 11 is a specific predetermined value. When the optical current sensor 10 is sensing the current, the signal processing circuit 11 electrically processes the optical signal from the optical current sensor 10 to measure the current.

Traffic red light monitoring system

Abstract: A pedestrian crossing (4) is controlled by a pair of traffic lights (1,2) and a stop line (3) is marked in front of the crossing . between the line and the crossing are inductive sensor loops (5-8) set into the surface. A camera records conditions at the crossing. The sensor and lights are coupled to a controller that evaluates and records to provide improved use.

Locking system for railway vehicle door locking safety control

Abstract: The system has a locking element (2) e.g. a bolt, with the locking position detected by two inductive sensors (S1,S2) arranged at a distance apart in the direction of displacement of the locking element. The separation distance of the sensors eliminates the possibility of their sensor regions overlapping. A transition state exists between the locking and unlocking positions. Each sensor is connected to a computer for signal evaluation.

Sensor system, method for manufacturing and self-test method

Abstract: there is provided a sensor system for detecting thermal radiation, comprising a substrate (15) and a plurality of sensor elements (10) on the substrate (15), said at least one self-test device (53) is provided in order to generate heat, with the one or more sensor elements (10) can be heated. the sensor elements (10) can be heated in accordance with a typical time pattern during the self-testing process. are also indicated an advantageous preparation process for the sensor system and an advantageous design of the entire system including the signal processing.

Inductuve sensor circuit

Abstract: The circuit has a pair of inductive sensor coils providing respective phase-shifted sinusoidal voltages (U1,U2) which are foltered via low-pass filters and coupled to respective inputs of a difference amplifier providing an output pulse sequence proportional to the detected rotation. The relative phase offset of the sensor coil voltages can be evaluated by the indictive sensor circuit for determining the travel direction of the vehicle.

Inductive coin validation system and payphone using it

Abstract: A coin validation arrangement, usable for example in pay telephones, uses one or more inductive sensors (17) having a small effective magnetic field so that the inductive sensor (17) responds only to the material of a strip across the coin. Preferably a plurality of inductive sensors (17) are used, mounted at different heights above the floor (23) of the coin guide, at different positions along the coin path. At each position along the coin path there may be either one or a plurality of inductive sensors (17). Preferably the inductive sensors (17) are surface mount inductors on a printed circuit board which forms part of one wall (19) of the coin guide. Such arrangements are particularly useful for recognising coins having an outer ring made of a different material from the central disc, and for distinguishing such coins from uniform composition coins.

Method and apparatus for commutating a three-phase variable reluctance motor

Abstract: A method and apparatus for exciting a three-phase variable reluctance motor is used, for example, as an encoder system to commutate a rotor. The system includes a power source, a position sensor and excitation electronics. The position sensor is adapted to generate a plurality of variable induction values corresponding to relative motor torque rankings and absolute angular positions of the rotor. Excitation electronics is provided electric communication with the inductive sensor and the power source and is adapted to generate digital values of the inductance values corresponding to the motor torque rankings. Excitation electronics includes steering logic responsive to the digital values to generate an output signal having a value corresponding to the phase of the motor to apply current to so as to commutate the rotor.

Micro-machined inductive sensor

Abstract: of EP0871012Micro-machined inductive sensor emits an alternating magnetic field in order to detect position and or movement of an object (O), which is capable of modifying the magnetic field, by means of a discontinuity (D,C). The sensor comprises a planar emitting coil (10), which radiates the alternating magnetic field and one or more planar receiving magnetic coils (11-14), arranged in such a manner as to capture a certain part of the radiating field and variations in the field caused by discontinuities in the object (O). The coils are machined on the common substrate by a selective photolithography process. In the areas where the emitter coil (10) is contiguous with the receiver coils (11-14) a shielding strip galvanically independent of the coils (10-14) is connected to a reference potential. The shielding strip is formed by deposition of a metal skin on the substrate.

Detection and localization of partial discharge in high voltage power cable joints

Abstract: Laboratory performance test of the high voltage power cable joints at lower voltages is not crucial, nor has the continuous monitoring of partial discharge (PD) been considered necessary. However for HV power cable joints at higher voltages, such as 420 kV, the reliable PD detection during performance test as well as the on-line continuous PD monitoring have been considered desirable to an increasing extent. Accordingly, a system was developed to facilitate such tasks. The system is based on decoupling of PD by means of inductive sensors, signal treatment and investigation according to a technique called INTECH, Inductive Measurement Technique. The laboratory system sensitivity is about 5 pC when the cable is not loaded with any power current and about 30 pC when the cable load is about 2000 A. The first prototype system was tested in the field on a 420 kV cable joint. This paper describes the system and presents some of the field test results.

Micro-machined sensor, particularly for displacement

Abstract: Micro-machined inductive sensor emits an alternating magnetic field in order to detect position and or movement of an object (O), which is capable of modifying the magnetic field, by means of a discontinuity (D,C). The sensor comprises a planar emitting coil (10), which radiates the alternating magnetic field and one or more planar receiving magnetic coils (11-14), arranged in such a manner as to capture a certain part of the radiating field and variations in the field caused by discontinuities in the object (O). The coils are machined on the common substrate by a selective photolithography process. In the areas where the emitter coil (10) is contiguous with the receiver coils (11-14) a shielding strip galvanically independent of the coils (10-14) is connected to a reference potential. The shielding strip is formed by deposition of a metal skin on the substrate.

Device for detecting the absence of a lid and for measuring a vacuum

Abstract: Detector located in the packaging chain after the closure process. It detects and individually isolates those containers, made from metal or glass, whose closure is defective owing to the absence of a lid or a vacuum. The detector centres the container by means of two discs mounted on shafts a direct reflection sensor will emit a beam, being reflected when a container interrupts it, producing a signal which, picked up by a transistor, will actuate an inductive sensor, actuating a dual-effect cylinder which will expel the container without a lid. Measurement of the vacuum. An inductive sensor emits a signal which is picked up by an electrovalve, activating a single-effect cylinder which will lower a mechanism of two discs with springs towards the lid. When the disc presses the lid, the sensor will emit a signal in accordance with the level of the vacuum.

Radioisotope proximity sensor

Abstract: A radioisotope proximity sensor is provided for detecting proximity or distance to a nearby object containing a small radiation source complementary to the sensor. The output of the sensor is amplified or compared to determine the distance or proximity. The radioisotope proximity sensor is unaffected by magnetic fields over the short sensing distances. It is also unaffected by environmental contamination when the appropriate radiosource/detector combination is used. The radioisotope proximity sensor is easily shielded from electrostatic or electromagnetic noise, and the radiation source can be small, easily incorporated, and requires no external power or connections to affect mechanical reliability or impede armature movement.

Characterization of a magnetic field sensor based on torque measuring

Abstract: A sensor for low frequency measurements of the magnetic field is presented in the paper. It is based on the measurements of an electromagnetic torque. An output directly proportional to the unknown magnetic field is produced, the method has the main advantage of avoiding the drifts present in the integration of signals from inductive sensors. The design and construction criteria, aiming at an uncertainty of few milliteslas in field measuring, are described. The analysis of the sensor linearity is presented in the paper together with the test rig, able to guarantee well reproducible conditions. The dynamic behavior of the torque based sensor is considered. It is studied either on the basis of the coil and load cell characteristics or analyzing the response to an applied known electromagnetic torque.

Optical sensor apparatus and signal processing circuit used therein

Abstract: An optical sensor apparatus capable of accurate measurement without using a filter circuit, and therefore being further capable of pulse driving an LED and thus reducing power consumption, is provided. To achieve such an optical sensor apparatus, when an optical current sensor 10 is not sensing the current to be measured, an optical current sensor signal processing circuit 11 first supplies dc light of a specific intensity to the optical current sensor 10, and then adjusts the intensity of the light so that the intensity of light returned from the optical current sensor 10 to the signal processing circuit 11 is a specific predetermined value. When the optical current sensor 10 is sensing the current, the signal processing circuit 11 electrically processes the optical signal from the optical current sensor 10 to measure the current.

Two-chip power integrated circuit with improved short circuit characteristics

Abstract: The invention relates to a two-chip power integrated circuit. According to the invention, a sensor chip (1) with a sensor is placed on a switch chip (1), said switch chip having a switch. The sensor is connected electrically to the switch so that said switch can be tripped through the sensor when the temperature detected by said sensor exceeds a pre-set limit value. At least one supply lead (5) of the switch is arranged close to the sensor so that the sensor chip (2) heats up more quickly.

Characterization of a magnetic field sensor based on torque measuring [for fusion diagnostics application]

Abstract: A sensor for low-frequency measurements of the magnetic field is presented in the paper. It is based on measurements of an electromagnetic torque. An output directly proportional to the unknown magnetic field is produced. This method has the main advantage of avoiding the drift present in the integration of signals from inductive sensors. The design and construction criteria, aiming at an uncertainty of a few milliteslas in field measuring, are described. The analysis of the sensor linearity is presented in the paper together with the test rig, able to guarantee reproducible conditions. The dynamic behavior of the torque-based sensor is considered. It is studied either on the basis of the coil and load cell characteristics or analyzing the response to an applied known electromagnetic torque.

Sensor arrangement producing one output signal depending on sensor internal resistance and another, depending on a measured variable

Abstract: The sensor circuit arrangement includes a sensor ( 23; 53 ) that produces an alternating voltage sensor signal that varies according to a measured variable; first and second current supplying circuits ( 21, 51 ) connected to respective sensor terminals to apply first and second output voltages (U 1, U 2 ) to the respective terminals; a counter-coupling network ( 24, 54 ) coupling the current supplying circuits to provide respective constant currents to the sensor ( 23, 53 ) and a sensor signal processing circuit portion. The sensor signal processing circuit portion includes an operational amplifier ( 13,46 ) connected across the sensor terminals, a low-pass filter ( 20,50 ) connected to the operational amplifier and a capacitor ( 19, 46 ) connected to the operational amplifier to generate an alternating output signal having an amplitude depending on the magnitude of the measured variable. The low-pass filter produces a filter output signal indicative of a temperature-dependent internal sensor resistance. The sensor is at an ungrounded floating potential so that common-mode interference is compensated.

Sensing matter on the surface of a capacitive sensor

Abstract: A capacitance sensor detects the absence/presence of physical matter on a sensing surface of the sensor. The capacitive sensor is a multi-cell sensor wherein each cell has one or more buried, protected, and physically inaccessible capacitor plates. The sensor is physically placed in an environment that is to be monitored for deposition of a particle, vapor, and/or drop of a foreign material on the sensing surface. All cells are initially placed in a startup condition or state. Thereafter, the cells are interrogated or readout, looking for a change in the equivalent feedback capacitance that results from an electrical field shape modification that is caused by the presence of physical matter on the sensing surface. When no such change is detected, the method is repeated for another cell. When a change is detected for a cell, a particle/vapor/drop output is provided. As an optional step, the sensor is provided with a layer of a material that is selectively reactive to or reactive with, a particle/vapor/drop of a known type of foreign material.

Detection of leakage currents arising from lightning conductors

Abstract: Device operates as a miniature transformer and comprises an inductive sensor (2) which is sensitive to the magnetic field produced by a leakage current from an earth conductor (12), called the primary. The sensor (2) produces an electric current, under the influence of the magnetic field, within the generator (24), which is called the secondary. An indicator (4) has a mobile shutter (14), which moves between two positions, conspicuous and neutral positions. The secondary current serves to move the shutter between neutral and conspicuous positions when there is a leakage current. The switch can only be reset manually by an operator.