Abstract: Provided is a variable reluctance type angle detector whose exciting winding resistance can be reduced to increase an exciting current without an increase in exciting power source voltage, thereby reducing an influence caused by a noise.

Abstract: The invention concerns the field of devices and appliances for measuring the intensity and the direction of the magnetic field emitted by a plate or a structure, such as for example a ship's hull and it particularly concerns a method for determining the magnetisation and the magnetic field radiated by a ferromagnetic plate using magnetic field sensors distributed along said plate and at known positions relative thereto.

Abstract: Systems and methods for detecting faults in RVDTs and LVDTs are described. In an exemplary embodiment, a sum of secondary voltages V1 and V2 from a transducer is obtained by adding the secondary voltages together, i.e.; V1+V2. This sum of secondary voltages theoretically should be constant for all LVDT/RVDT positions, since the total length of the secondary transformer is constant. An electrical fault in the primary or secondary windings generates a corresponding change in the sum of secondary voltages. By comparing this shifted value to a reference value which is representative of a no-fault condition, an error value is created which indicates the magnitude of the shift in the sum of the secondary values. Depending upon the magnitude of the error value, certain actions are taken.

Abstract: A device for detecting the displacement of an object comprising a ferromagnetic material, comprises a magnetic circuit generator provided with first and a second cores made of ferromagnetic material and an excitation coil and a measurement coil. The magnetic circuit generator is connected to a detecting unit designed to detect a reluctance variation brought about in the circuit by the displacement of the object and to deduce therefrom its position. In the device, the magnetic circuit generator comprises first and second transformers with open magnetic circuit, the transformers being juxtaposed and comprise each an axis extending across their respective core, the axes extending substantially perpendicular to the path. The excitation coil comprises two coils connected in series which form the primary windings of the first and second transformers.

Abstract: A two-dimensional all-digital ratiometric decoder to analyze signals representative of state changes in a closed loop control system. In one embodiment, the two-dimensional digital ratiometric decoder comprises at least one selector circuit, a summation circuit, a difference circuit and a divider circuit. The at least one selector circuit is adapted to select the signals to be processed by alternating between the signals representative of the X dimension and the signals representative of the Y dimension. The summation circuit is adapted to add the amplitude magnitudes of the signals selected. The difference circuit is adapted to obtain the difference between the amplitude magnitudes of the signals selected. The divider circuit is adapted to divide the output of the difference circuit by the output of the summation circuit to produce a quotient proportional to the physical change of the object being controlled.

Abstract: A deviation angle detector enlarges the application range by enlarging the detectable deviation angle range. The deviation angle detector has two resolvers, which have rotors, stators, and single excitation windings and multiple output windings that are coiled around the stators. The difference in rotation angles of the resolvers is detected as a deviation angle ?? by calculating the output signal that corresponds to the rotation angles of the resolvers digitally or in analog. The corresponding output windings of the resolvers are connected in series and the output signals are extracted from the serially connected output windings and calculated digitally or in analog.

Abstract: Inductive proximity switch has a first transmitting coil (S1) and a first receiving coil (E1) of a receiving coil arrangement. The transmitting coil (S1) transmits an exciting field inducing eddy currents in a metallic trip (1) brought into the vicinity of the proximity switch. The eddy currents generate a voltage-inducing eddy current field in the first coil (E1) of the receiving coil arrangement. The first coil E1 and a second coil (E2) of the receiving coil arrangement are disposed and connected so that the exciting field generates a differential voltage (3), in the receiving coil arrangement. A pair of compensating coils includes the second coil (E2) of the receiving coil arrangement and a compensating coil (S2) connected in series with the transmitting coil (S1), the pair of compensating coils being isolated from the eddy current field.

Abstract: With a magnet arrangement for an electromechanical drive with a cylindrical armature guided in a pole tube, the position of the armature is transformed into an electrical signal. Provided for this is a displacement sensor which is connected to the armature and has a fixed part and a movable part. One side of the armature is formed such that it transfers the movement of the armature, and the other side of the armature is connected to the movable part of the displacement sensor. The pole tube is provided with a closure part on the side of the displacement sensor. A pressure tube is led to the outside through an axial clearance of the closure part. The movable part of the displacement sensor moves in the pressure tube. The pressure tube is enclosed by the fixed part of the displacement sensor. In order to prevent the displacement sensor from being damaged by vibrations, the fixed part of the displacement sensor is arranged in a clearance of the closure part.

Abstract: In a circuit arrangement having a linear variable differential transformer as a displacement sensor or force sensor, having a selection circuit which is connected to the primary coil of the transformer and which provides an output current for triggering the primary coil, and having an analysis circuit which is connected to the secondary coils of the transformer and which provides a message signal, a control circuit used for triggering the selection circuit and the analysis circuit and for processing the measurement signal provided by the analysis circuit is connected to the primary coil in order to calculate the temperature of the circuit arrangement, and is configured such that it determines the temperature-dependent ohmic resistance of the primary coil and calculates from it the temperature and corrects accordingly the measurement signal provided by the analysis circuit.

Abstract: A linear variable transformer (LVDT) for use in a transducer. The LVDT has a non-ferromagnetic core which may eliminate Barkhausen noise and thereby improve the sensitivity of the resulting measurements. In one aspect, this system may be used in an atomic force microscope.

Abstract: A rotary input for a linear variable differential transformer (LVDT) system connects to a gear reduction system. The gear reduction produces a reduced rotary output in a rotary output member. The output member is threaded, and a nut is threaded onto the output member. Therefore, the nut translates as the rotary output member rotates. The armatures of one or more LVDTs attach to the nut. Each armature contains a magnetic member. As the nut translates along the threaded output member, the nut translates the armatures. Armature movement moves the magnetic members to create a differential voltage between the secondary coils of the LVDT.

Abstract: A displacement sensor for sensing the relative position of an object to be detcted is provided. The displacement sensor includes a core body having a core center portion and core end portions that are continuously formed on both sides of the core center portion. Magnetizing coils and detecting coils are wound around the core body such that they are lined on an axis of the core body. One of the magnetizing coils and detecting coils is placed at the core center portion while the other ones of the magnetizing coils and detctin coils are placed at the core end portions in the axial direction. The width of the core end portions in the direction perpendicular to the axial direction of the core body is substantially the same and is smaller than the width of the core center portion.

Abstract: The invention relates to a method and to a circuit for detecting the armature position of an electromagnet. The magnetic voltage is compared with a reference voltage. The reference voltage is used derived from the magnetic voltage by a filtration.

Abstract: An inductive displacement sensor having a displaceable or rotatable, magnetically permeable measuring head, at least one measuring loop whose geometric shape varies in response to the longitudinal/rotary displacement of the measuring head, and at least one excitation loop by which a magnetic flux can be generated in the measuring head. The flux penetrates the at least one measuring loop at any point of the longitudinal/rotary displacement, essentially in the region of the measuring head, and inducing an electric measuring signal (i2). A resonant circuit, which is electrically decoupled from the outside, is arranged on the measuring head and is excited in correct phase relation by a short voltage pulse after a number of, preferably, 10 to 20 free oscillations.

Abstract: A rotary input for a linear variable differential transformer (LVDT) system connects to a gear reduction system. The gear reduction produces a reduced rotary output in a rotary output member. The output member is threaded, and a nut is threaded onto the output member. Therefore, the nut translates as the rotary output member rotates. The armatures of one or more LVDTs attach to the nut. Each armature contains a magnetic member. As the nut translates along the threaded output member, the nut translates the armatures. Armature movement moves the magnetic members to create a differential voltage between the secondary coils of the LVDT.

Abstract: A transmitter system for a Ferraris motion transmitter, includes a magnetic measuring arrangement including at least one magnetic field generator for generating a magnetic field and an electrically conductive measuring body, with the magnetic field generator and the measuring body movable relative to one another in operation. Coupled to the magnetic measuring arrangement is a magnetic field sensor for providing an output signal commensurate with a velocity or acceleration of the measuring body. At least one of the magnetic field generator and the magnetic field sensor includes at least two magnetic members interlocking one another in concentric relationship to the measuring body for guiding the magnetic field as a result of eddy currents forming during operation.

Abstract: Analog circuitry is disclosed for conditioning a signal from linear and rotary variable differential transformers having a primary winding, a pair of secondary windings and a movable core. The circuitry includes a unique closed loop negative feedback mechanism which, over time, adjusts the frequency of a voltage controlled oscillator so that a steady-state condition is achieved within the circuitry, whereby the total integrated value of the secondary winding voltages at an integrator remains equal to a reference voltage, thereby reducing the computational burden associated with solving an equation to determine the position of the movable core of the transformer.

Abstract: In a circuit arrangement having a linear variable differential transformer as a displacement sensor or force sensor, having a selection circuit which is connected to the primary coil of the transformer and which provides an output current for triggering the primary coil, and having an analysis circuit which is connected to the secondary coils of the transformer and which provides a message signal, a control circuit used for triggering the selection circuit and the analysis circuit and for processing the measurement signal provided by the analysis circuit is connected to the primary coil in order to calculate the temperature of the circuit arrangement, and is configured such that it determines the temperature-dependent ohmic resistance of the primary coil and calculates from it the temperature and corrects accordingly the measurement signal provided by the analysis circuit.

Abstract: A magnetically variable differential transformer, comprising: a primary winding; a first secondary winding; a second secondary winding; a non-movable permeable core disposed within the primary winding, the first secondary winding and the second secondary winding; and a movable magnet configured for movement about the primary winding, the first secondary winding and the second secondary winding, wherein movement of the movable magnet causes magnetic saturation of portions of the non-movable permeable core.

Abstract: A Position Sensor comprises: one or more excitation windings; a signal generator adapted to apply excitation signals to the or each excitation winding; tag means displaceable relative to said excitation windings; one or more sensor windings electromagnetically coupled to said excitation windings such that in response to said excitation signals being applied to said excitation windings, there is generated sensed signal in the or each sensor winding; and a signal processor adapted to process said sensed signals to determine the position of said tag means in any location in the X, Y and Z planes essentially in accordance with phase values or in accordance with phase values and amplitude values.

Abstract: The invention concerns a device for detecting the displacement of an object comprising a ferromagnetic material. Said device comprises a magnetic circuit generator provided with first and a second cores made of ferromagnetic material and an excitation coil and a measurement coil. The magnetic circuit generator is connected to a detecting unit designed to detect a reluctance variation brought about in the circuit by the displacement of the object and to deduce therefrom its position. In said device the magnetic circuit generator comprises first and second transformers with open magnetic circuit, said transformers being juxtaposed and comprise each an axis extending across their respective core, said axes extending substantially perpendicular to said path. The excitation coil comprises two coils connected in series which form the primary windings of the first and second transformers.

Abstract: A transducer (10) for distance measurement, especially between a stator and a rotor in a refiner for paper pulp production, in which the transducer is of the magnetic type and has a tubular casing (17), the one end of which forms a measuring head (14), in which a measuring pole (15) is fitted in a holder (16) which is mounted in the end of the casing (17) and seals this. The holder (16), with a first portion (22) of its axial length, reaches beyond the end of the casing. This first portion (22) and the measuring pole (15) are intended to be able to be worn away to a smaller axial length during use of the transducer, whilst the length of the casing is maintained.

Abstract: A circuit for a displacement detector having a contact sensor with a sensor coil forming a differential transformer is disclosed. The circuit includes a driver for generating a driving signal for driving the sensor coil, a standard signal processor for processing the driving signal and outputting a standard signal, an output signal processor for processing signals outputted from the differential transformer, a differential amplifier for carrying out differential amplification of the standard signal and the output signal from the output signal processing means, and an amplitude adjustor for adjusting the amplitude of the driving signal for the sensor coil to a constant value by feeding back the standard signal to the driver.

Abstract: Detector circuitry for detecting magnetic field disturbances resulting from the movement of equipment through a pipe of magnetic material, the detector circuitry comprising a difference circuit fed with the outputs of two longitudinally spaced sensor means via respective DC blocking means, a saturating difference amplifier feeding an integrator and fed with the outputs of the difference circuit and the integrator, and indicating means fed from the integrator. The detector circuitry may also including level setting means and a comparator fed with the outputs of the integrator and the level setting means and feeding the indicating means. A second comparator may be connected in parallel with the first comparator and fed with the inverse of the output of the level setting means and the output of the integrator.

Abstract: An offset signal for failure detection, that cannot be removed if an input signal line is broken is applied from an offset application circuit with output impedance higher than impedance of a differential transformer to an output signal of the differential transformer. A drive signal applied to a differential transformer is generated in digital form and an offset correction and a gain correction to output of the differential transformer are made in digital form for making controls necessary.

Abstract: A displacement detector has a contact sensor incorporating a differential transformer and a circuit for adjusting the amplitude of the driving signal for driving a differential transformer of the sensor by feeding back as a standard signal the driving signal through an amplifier and an AC-DC converter as a standard signal. The sensor has a housing containing a mobile member. The mobile member has a shaft with a hole. An outer tubular body of a linear bush and a ball guide each have a hole, and a pin is inserted through these holes movably in the direction of movement of the mobile member such that the rotation of the mobile member is prevented.

Abstract: A method for forming a non-contact position sensor having a predetermined stroke length comprises providing a pair of coil assemblies each comprising a primary and secondary coil of a predetermined size; providing a core member of varying magnetic density about its length; and inserting the core member within the coil assemblies, whereby axial movement of the core member relative to the coil assemblies causes a corresponding output signal from the coil assemblies indicative of the position of the core member.

Abstract: A transducer that reduces noise, increases sensitivity, and improves the time response of a linear variable differential transformer (LVDT). The device replaces the primary coil and the high permeability ferromagnetic core of conventional LVDTs with a primary wound around a moving non-ferromagnetic core. In addition to reducing or eliminating Barkhausen noise, this approach reduced or eliminated a number of other undesirable effects in conventional LVDTs including excessive eddy current heating in the core, non-linearities associated with high permeability materials and the length scale of the flux circuit. These improvements are coupled with improved LVDT signal conditioning circuitry. The device is also an actuator and may be used to convert differential voltages into force.

Abstract: The present invention provides for a metallic surface identifying sensor including: a magnetic pole portion for detection which shifts facing a surface of a magnetic body to be identified having an uneven shape wherein the distance from the surface to be identified changes along with the uneven shape while shifting; a reference magnetic pole portion which is placed across from a reference surface, wherein the distance from the reference surface to the magnetic pole portion is maintained approximately constant regardless of the shifting of the magnetic pole portion for detection in relation with the surface to be identified; magnetizing coils which are separately wound around the magnetic pole portion for detection and the reference magnetic pole portion to generate magnetic fluxes; and detecting coils which are separately wound around the magnetic pole portion for detection and the reference magnetic pole portion to detect the magnetic fluxes wherein the uneven shape of the surface to be identified of the met

Abstract: Techniques for coupling with devices that convert displacements into differential voltages and improve the sensitivity of such devices. The disclosed system improves the accuracy and resolution of a transducers such as an LVDT by converting certain parts of the circuit to a digital circuit. One embodiment uses a processor, although other digital processing circuitry may also be used.

Abstract: A displacement detector has a contact sensor incorporating a differential transformer and a circuit for adjusting the amplitude of the driving signal for driving a differential transformer of the sensor by feeding back as a standard signal the driving signal through an amplifier and an AC-DC converter as a standard signal. The sensor has a housing containing a mobile member. The mobile member has a shaft with a hole. An outer tubular body of a linear bush and a ball guide each have a hole, and a pin is inserted through these holes movably in the direction of movement of the mobile member such that the rotation of the mobile member is prevented.

Abstract: A probe (10) for sensing movement of a body of magnetic material comprises a magnetically energisable pole piece (30), a closed loop electrical circuit (20) having a first end (25) which is wound around the pole piece (30) and forms a pole piece coil (25) inductively coupled to the pole piece, the arrangement being such that movement of a body of magnetic material (70) relative to the pole piece (30)induces a current in the closed loop circuit (20), and a second end (45), remote from the pole piece (30), which forms a transformer primary coil. A transformer secondary coil (65) is inductively coupled to the primary coil (45), and terminated by a load resistance and means for measuring an output signal from the secondary coil. The primary (45) and secondary (65) coils form a transformer such that a current in the primary coil induces a voltage across the secondary coil. One or more shorting turns (60) of a conductor are inductively coupled to the primary (45) and secondary (65) coils.

Abstract: A electromagnetic induction-type absolute position transducer according to the present invention has a plurality of scale loops functioning as coils. The scale loop has first and second loop portions and a connecting pattern portion which connects the corresponding first and second loop portions with each other. The first and second loop portions are arranged along the measuring axis at different wavelength intervals. At least part of the pattern widths constituting scale loops are gradually increased as the length of a connecting pattern portion becomes longer.

Abstract: An inductive length measuring system which, by scanning a scale with a graduation of periodically variable reluctance and a coil system in a linear arrangement, can detect information relating to the position and/or the movement of the coil system with reference to the scale. The coil structure comprises a multi-ply arrangement of a combination of coils in the form of planar spiral windings or turns having a plurality of receiver pairs, each pair having two differentially connected receiver elements which can be interconnected for the purpose of signal generation for each of at least two measuring channels, and wherein at least one emitter element is provided which is inductively coupled to the receiver elements as a function of the relative position in the measuring direction relative to the measuring scale, thereby generating at least one output signal which is compensated for offset and/or sinusoidal shape and/or amplitude.

Abstract: A linear variable differential transformer (LVDT) assembly comprises a housing. A tube extends into the housing. An armature mounts inside of the tube and can move longitudinally within the tube. A coil assembly, which includes a primary coil and two secondary coils mounts on the outside of the tube. The coil assembly has adjustable connection with the housing. Consequently, the coil assembly can be adjusted longitudinally with respect to the armature until the LVDT is in the null position. That occurs when the differential voltage from alternating current through the secondary coils is zero.

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: Single coil to be excited by a predetermined A.C. signal is provided, with no secondary coil being provided. Magnetism-responsive member is movable relative to the coil so that a self-inductance of the coil progressively increases or decreases in response to displacement of an object to be detected within a predetermined range and a voltage of the coil corresponding to the self-inductance is produced. Predetermined reference voltage is generated and subjected to analog operations with the coil output voltage, to thereby generate first and second A.C. outputs having, as amplitude coefficients, first and second cyclic amplitude functions correlated to the position to be detected. The position is detected on the basis of the phase component of the amplitude coefficient functions. Combination of two coils and one reference voltage may be employed.

Abstract: Single coil to be excited by a predetermined A.C. signal is provided, with no secondary coil being provided. Magnetism-responsive member is movable relative to the coil so that a self-inductance of the coil progressively increases or decreases in response to displacement of an object to be detected within a predetermined range and a voltage of the coil corresponding to the self-inductance is produced. Predetermined reference voltage is generated and subjected to analog operations with the coil output voltage, to thereby generate first and second A.C. outputs having, as amplitude coefficients, first and second cyclic amplitude functions correlated to the position to be detected. The position is detected on the basis of the phase component of the amplitude coefficient functions. Combination of two coils and one reference voltage may be employed.

Abstract: A scale loop formed by a loop trace of electrically conductive material is usable in an induced current position transducer. The scale loop is continuous and has a particular shape depending on the configuration of the induced current position transducer. The scale loop is not in contact with other highly conductive materials. The dimensions of the cross-section of the conducting trace are chosen to increase the transfer of energy through the transducer.

Abstract: A magnetic displacement sensor device includes a plurality of magnetic displacement sensors, each of the magnetic displacement sensors having at least one coil wound thereon, and a single common excitation oscillator connected to each of the coils wound on the respective magnetic displacement sensors. Each of the coils are excited at the same oscillatory frequency and in the same phase by the single common excitation oscillator.

Abstract: The present invention is intended to provide a ultra-precision high sensitivity displacement measuring device which has such a high resolution as to be able to make submicron measurement.

Abstract: A transducer that reduces noise, increases sensitivity, and improves the time response of a linear variable differential transformer (LVDT). The device replaces the primary coil and the high permeability ferromagnetic core of conventional LVDTs with a primary wound around a moving non-ferromagnetic core. In addition to reducing or eliminating Barkhausen noise, this approach reduced or eliminated a number of other undesirable effects in conventional LVDTs including excessive eddy current heating in the core, non-linearities associated with high permeability materials and the length scale of the flux circuit. These improvements are coupled with improved LVDT signal conditioning circuitry. The device is also an actuator and may be used to convert differential voltages into force.

Abstract: The invention relates to a method for determining the position and/or the speed of motion of a control element which can be moved back and forth between a first and second switching position. According to said method, an immersion body which is connected to the control element is guided through at least one stationary plunger coil, synchronously with the motion of said control element. The voltage that is generated as a result of the immersion body moving in relation to a permanent magnet and/or a permanent magnet moving in relation to the plunger coil is detected as a signal for the speed of motion of the control clement. The changes in impedance and or a current that are caused as a result of the movement of the immersion body in the plunger coil are detected as a signal for the position of the control element.

Abstract: An LVDT assembly measures movement of a linkage. The LVDT assembly includes multiple LVDT units mounted in parallel to an LVDT input member for concurrent operation. The LVDT assembly also includes a rotary head that has a threaded portion that is secured to the linkage by rotating the head and engaging mating threads on the linkage and on the rotary head. A conventional ball bearing assembly is provided between the rotary head and the stationary input member. A metallic ball is between the rotary head and the input member. A set screw engages the ball. Tightening the set screw stresses transmits a force from the set screw, the ball and the input member to stress the ball bearing. The stress substantially eliminates backlash between the rotary head and the LVDT input member.

Abstract: An absolute angular sensor of a steering system for vehicles, which includes a power supply for supplying power, a pulse supply for generating pulses, a linear variable displacement transducer operated by a pulse outputted from the pulse generator for sensing a variable displacement of a rotator disc mounted at a steering shaft when the steering shaft operates, and outputting a signal in proportion to the sensed rotation displacement, a demodulator for demodulating the outputted signal from the linear variable displacement transducer, a DC (Direct Current) amplifier for amplifying the rectified external displacement from the demodulator into a certain level, and a DC output part for providing a signal output amplified by the DC amplifier, whereby it is possible to sense an absolute position accurately and an absolute angle of the steering shaft accurately.

Abstract: Disclosed are inductive linear and angle sensors for motor vehicles, which include an oscillator circuit for generating a periodic alternating-voltage signal; an exciting coil coupled to the oscillator circuit; several receiving coils; an evaluating circuit for evaluating signals induced in the receiving coils; and one movable inductive coupling element which influences a strength of inductive coupling between the excitation coil and the receiving coils. The one movable inductive coupling element of each sensor is varied in form to reduce residual error, which occurs during operation.

Abstract: This Inductive Displacement Transducer relates to a new and useful set of embodiments for a comparator-type relaxation oscillator circuit where the frequency is controlled by variable inductance. Each oscillation of said circuit discharges a fixed amount of charge such that an increase in frequency increases the total current draw of the circuit.

Abstract: The present invention is intended to provide a ultra-precision high sensitivity displacement measuring device which has such a high resolution as to be able to make submicron measurement.

Abstract: An inductive absolute position sensor has at least one magnetic field generator that generates a first changing magnetic flux in a first flux region. A plurality of coupling loops have a first plurality of coupling loop portions spaced at an interval related to a first wavelength along a measuring axis and a second plurality of coupling loop portions spaced at an interval related to a second wavelength along a measuring axis. One of the first plurality of coupling loop portions and the second plurality of coupling loop portions are inductively coupled to a first changing magnetic flux from a transmitter winding in a first flux region to generate a second changing magnetic flux outside the first flux region in the other of the first plurality of coupling loop portions and the second plurality of coupling loop portions. A magnetic flux sensor is positioned outside the first flux region and is responsive to the second changing magnetic flux to generate a position-dependent output signal.

Abstract: An encoder comprises position detecting device for detecting a magnetic pole position and a rotational position of a motor. The encoder also includes a memory portion for storing parameter information particular to the motor or the position detecting device. A transmitting portion of the encoder is provided for externally transmitting parameter information particular to the position detecting device as a differential signal. A transmission suspension request detecting device is provided for detecting that the differential signal is driven by a given signal externally provided such that the differential signal does not exist as a transmission signal and for generating a transmission suspension request signal requesting suspension of transmission of the differential signal.