Abstract: The invention provides a highly accurate and inexpensive electromagnetic induction type encoder capable of acquiring strong signal intensity with the offset reduced by a short scale coil, and is durable against fluctuations in the yaw direction, which includes a number of scale coils 14 arrayed on a scale 10 along the measurement direction, and transmitting coils 24 and receiving coils 20 that are disposed on a grid 12 relatively movably in the measurement direction with respect to the scale, and which detects a relative movement amount of the scale and the grid from changes in magnetic fluxes detected by the receiving coils via the scale coil when the transmitting coils are magnetized, wherein a plurality of sets of the transmitting coils (24A, 24B), the receiving coils (20A, 20B) and the scale coils (14A, 14B) are disposed symmetrically with respect to the center of the scale, and scale coils of one set located at a symmetrical position around the center of the scale is disposed with ½ phase of the scale pi

Abstract: Provided is an electromagnetic tracking system, comprising a coil arrangement comprising a first coil configured to generate a first magnetic field and a second coil configured to generate a second magnetic field and a drive unit configured to provide a first drive current to the first coil and to provide a second drive current to the second coil, wherein the first drive current and the second drive current are at about the same frequency, wherein the frequency is below 60 Hz, and wherein the first electromagnetic field and the second magnetic field are generated out of phase.

Abstract: Sensor circuits including an oscillator circuit.

Abstract: Methods of reorienting ferromagnetic layers of a plurality of magnetoresistive elements and structures formed by the methods. The plurality of magnetoresistive elements, preferably GMR multilayer elements, are manufactured and arranged on a planar substrate. The method effectively allows selective orientation and reorientation of distinct ferromagnetic layers of a subset of the magnetoresistive elements on the substrate. The methods make either use of subsequent annealing processes making use of magnetic fields pointing in different directions. Prior to application of a subsequent annealing process, a complimentary subset of magnetoresistive elements is effectively shielded by selective deposition of a soft-magnetic shielding layer. Alternatively, a single annealing process can be performed when an externally applied magnetic field is locally modified by soft-magnetic structures, such as fluxguides.

Abstract: A displacement measuring device includes a stationary magnetic member for providing an accommodation space and a first and second magnetic circuits, a movable magnetic member disposed in the accommodation space to move in its longitudinal direction, a magnetic sensor for sensing magnetic flux flowing in the first and second magnetic circuits. The stationary member includes a sensor supporting member disposed in line with an axis of symmetry, a pair of yoke members axisymmetrically disposed at opposite sides of the sensor supporting member, a pair of permanent magnets each of which is disposed between one of the yoke members and the sensor supporting member. The permanent magnets are polarized so that magnetic flux flows in one of the magnetic circuits opposite in direction to magnetic flux flowing in the other magnetic circuit. The magnetic sensor is disposed on the sensor supporting member to confront the moving magnetic member at a first air gap.

Abstract: The invention relates to position sensors of the linearly variable induction difference type. When cost constraints prevent the use of transformers with guaranteed phase-shift tolerance to achieve an accuracy objective, it is advantageous to provide an independent demodulation of the signals of the two windings. The error signal thus has a lower dependence on the phase shift and the accuracy is typically enhanced by a factor greater than an order of magnitude.

Abstract: A balancing circuit for a metal detector. The metal detector includes an oscillating power source, a transmit coil connected to the oscillating power source, first and second receive coils inductively coupled to the transmit coil, a first amplitude balancing circuit connected to the first receive coil, and a first phase balancing circuit connected to the first receive coil. The first phase balancing circuit includes a capacitor and a variable resistor.

Abstract: A system for determining magnetic permeability of a material. Two electrical inductors formed as primary and secondary concentric coils share a common magnetic core space. A first AC voltage applied to the primary coil creates a magnetic flux in the core proportional to the magnetic permeability of the material. The magnetic flux induces an AC voltage in the secondary coil indicative of the apparent magnetic permeability of the sample. The apparent permeability is corrected for conductivity by imposing a second AC voltage and resistor in series across first and second electrodes disposed in the material. When the material is a magnetorheological fluid, the magnetic permeability is proportional to the concentration of magnetic particles in the sample and can be back-calculated from the amplitude of the secondary voltage signal.

Abstract: Provided is a method for testing a head element that enables proper evaluation of the head element based on a characteristic of the head element under high-temperature and high-stress conditions. The testing method can be performed on a thin-film magnetic head including a head element and a heating element capable of applying a heat and stress to the head element, or performed on a row bar or a substrate wafer on which a plurality of the head elements and a plurality of the heating elements are disposed. The testing method comprises the steps of: causing the heating element to generate heat to apply a heat and stress to the head element; and measuring a characteristic of the head element under the heat and stress to evaluate the head element.

Abstract: A marine electromagnetic sensor cable includes a plurality of sensor modules disposed at spaced apart locations along a cable. Each module includes at least one pair of electrodes associated with the module. The electrodes are arranged to measure electric field in a direction along the direction of the cable. The cable is arranged to form a closed pattern. Another marine electromagnetic sensor cable includes a plurality of sensor modules disposed at spaced apart locations along a cable. Each module includes at least one pair of electrodes associated therewith. The electrodes are arranged to measure electric field in a direction along the direction of the cable. A plurality of spaced apart magnetic field sensors is associated with each module and arranged to enable determining an electric field amplitude in a direction transverse to the direction of the cable from magnetic field gradient.

Abstract: A position encoder is provided for indicating the relative position between first and second relatively move members. One of the members carries a magnetic field generator which generates a magnetic field whose magnitude and direction vary with position. In a preferred embodiment, the other member carries an excitation winding, one or more sensor windings and a film of magnetizable material. The arrangement is such that the positionally varying magnetic field interacts with the film to change the mutual coupling between the excitation winding and the or each sensor winding. Excitation and processing circuitry is provided for energising the excitation winding and for processing the sensor signals to determine a value indicative of the relative position between the first and second relatively movable members.

Abstract: A method and system for measuring formation resisitivity is achieved by introducing one or more continuous phase modulated electrical signals into the formation, each signal introduced at a different location. The current of each introduced electrical signal is then sensed, producing an analog voltage signal as a measurement of the formation. Each introduced electrical signal is compared with its respective measured signal of the formation. Each comparison is made in a quadrature demodulation device, producing an in-phase demodulated signal. A quasi-direct-current signal is extracted from each in-phase demodulated signal, producing an analog measurement related to the resistivity of the formation. Each analog measurement is converted into a digital value for further processing. Successive measurements are digitally summed and averaged to increase the signal to noise ratio.

Abstract: Multiple SQUID magnetometers that include at least two SQUID loops, each of which is composed of at least two Josephson Junctions connected in parallel with superconducting wires, are provided. The SQUID loops are fabricated such that they share a common Josephson Junction. Devices and application that employ the multiple SQUID magnetometers are also provided.

Abstract: A method for determining reservoir formation properties that consists of exciting the reservoir formation with an electromagnetic exciting field, measuring an electromagnetic signal produced by the electromagnetic exciting field in the reservoir formation, extracting from the measured electromagnetic signal a spectral complex resistivity as a function of frequency, fitting the spectral complex resistivity with an induced polarization model and deducing the reservoir formation properties from the fitting with the induced polarization model.

Abstract: A sonde includes an elongate flexible ferromagnetic core and a coil surrounds an intermediate segment of the core. A housing surrounds and supports the coil. An electronic drive circuit is mounted in the housing for supplying the coil with an electric signal that will induce the core to emit electromagnetic signals at a predetermined strength and frequency that can be remotely detected. Self-contained battery powered float-type and pill-type sondes are also disclosed.

Abstract: A sensor measures the position of an actuator of an internal combustion engine, wherein the actuator is electromotively driven by means of a drive connection. The housing of the actuator accommodates at least one position sensor which detects the position at the drive connection. At least one position sensor is connected to a circuit with an operating voltage source and receives signals from at least one position sensor. The circuit and the at least one position sensor are connected via a cable that conducts voltage and signals. The circuit comprises also at least one current measuring device connected in series to the operating voltage source. A current change is transmitted via the cable by means of the signals generated by the at least one position sensor depending on the position of the actuator.

Abstract: A rotational angle detecting device has a pair of permanent magnets and an angle sensor. Electrical connecting terminals are connected to the angle sensor and further connected to conductors. The conductors have seconds ends opposite to the first ends and serving as connector terminals of the connector. In one embodiment, the rotational angle detecting device includes a first resin-molded portion and a second resin-molded portion. The first resin-molded portion includes at least the electrical connecting terminals, a part of the angle sensor and the first ends of the conductors embedded within a first resin. The second resin-molded portion includes portions of the conductors embedded within a second resin. In another embodiment, capacitors are connected to the connector conductors. The angle sensor has a magnetic detecting element positioned substantially perpendicularly to the rotational axis of the rotary section.

Abstract: A magnetoresistive (MR) sensing device includes MR elements electrically connected to form a bridge circuit and one or more non-functional (or “dummy”) MR elements for improved matching of the bridge circuit MR elements.

Abstract: The invention relates to a device for compensating for magnetic fields which has two sensors which are active in different frequency ranges and thus allows regulation with a bandwidth from 0 to 20 kHz.

Abstract: A sensing device includes a circuit that compensates for time and spatial changes in temperature. The circuit includes elements to correct for variation in permeability of a highly permeable core of a differential variable reluctance transducer as temperature changes. The circuit also provides correction for temperature gradients across coils of the transducer.