7311 results about "Eddy current" patented technology

A composite magnetic core formed of a high permeability material and a lower permeability, high saturation flux density material prevents core saturation without an air gap and reduces eddy current losses and loss of inductance. The composite core is configured such that the low permeability, high saturation material is located where the flux accumulates from the high permeability sections. The presence of magnetic material having a relatively high permeability keeps the flux confined within the core thereby preventing fringing flux from spilling out into the winding arrangement. This composite core configuration balances the requirements of preventing core saturation and minimizing eddy current losses without increasing either the height or width of the core or the number of windings.

An implantable medical device system advantageously utilizes low frequency (e.g., about 1-100 kHz) transcutaneous energy transfer (TET) for supplying power from an external control module to an implantable medical device, avoiding power dissipation through eddy currents in a metallic case of an implant and / or in human tissue, thereby enabling smaller implants using a metallic case such as titanium and / or allowing TET signals of greater strength thereby allowing placement more deeply within a patient without excessive power transfer inefficiencies.

A non-contact power charging system includes a wireless power transmission apparatus 10 for transmitting a power signal from a primary core 14 via a resonant converter 13 by the control of a transmission control unit 12; and a wireless power receiving apparatus 20 for receiving the power signal transmitted from the primary core 14 of the wireless power transmission apparatus 10 via a secondary core 24 and charging a battery cell 21 by the control of a receiving control unit 22. The wireless power receiving apparatus 20 includes a receiving shield panel 25 and an eddy current reducing member 26 in the side of the secondary core 24 to shield an electromagnetic field generated from the secondary core 24, to thereby protect the charging system and the battery pack from the electromagnetic field.

The present invention provides a thin film write head having an improved laminated flux carrying structure and method of fabrication. The preferred embodiment provides laminated layers of: high moment magnetic material, and easily aligned high resistivity magnetic material. In the preferred embodiment, the easily aligned laminating layer induces uniaxial anisotropy, by exchange coupling, to improve uniaxial anisotropy in the high moment material. This allows deposition induced uniaxial anisotropy by DC magnetron sputtering and also provides improved post deposition annealing, if desired. It is preferred to laminate FeXN, such as FeRhN, or other crystalline structure material, with an amorphous alloy material, preferably Co based, such as CoZrCr. In the preferred embodiment, upper and lower pole structures may both be laminated as discussed above. Such laminated structures have higher Bs than structures with insulative laminates, and yokes and pole tips and may be integrally formed, if desired, because flux may travel along or across the laminating layers. The preferred embodiment of the present invention improves soft magnetic properties, reduces eddy currents, improves hard axis alignment while not deleteriously affecting the coercivity, permeability, and magnetostriction of the structure, thus allowing for improved high frequency operation.

This invention has an object to a planar coil, a contactless electric power transmission device using the same. This planar coil is configured to suppress an eddy current developed between adjacent turns of wire for minimizing adverse effects on ambient electrical appliances resulting from heat generation. The planar coil 1 in the present invention is formed of spiral shaped wire 7 coated with thinned insulative film, in which adjacent turns of the wire 7 are spaced in radial direction at such a predetermined interval to suppress an eddy current. This planar coil 1 is preferably employed as a power transmission coil or power receiving coil.

An implantable electronic medical device is compatible with a magnetic resonance imaging (MRI) scanner. The device has a housing with exterior walls, each formed by a dielectric substrate with electrically conductive layers on interior and exterior surfaces. A series of slots divide each layer into segments. Segmenting the layers provides high impedance to eddy currents produced by fields of the MRI scanner, while capacitive coupling of the segments provides radio frequency shielding for components inside the housing. Electrical leads extending from the housing have a pair of coaxially arranged conductors and traps that attenuate currents induced in the conductors by the fields of the MRI scanner.

This invention constructs an antenna matching circuit able to avoid a bad influence when a conductor, such as a metal, or tag, approaches a reader / writer, and dissolves a communication defect area on the reader / writer and stably maintains a communication distance. In this invention, in a RFID system, when the tag corresponds to the generating area of a magnetic field of the reader / writer, a radio wave for sending information to the reader / writer is outputted by operating a control circuit of the tag by electric power generated in an antenna coil of this corresponding tag. A conductor is arranged near the antenna coil of the reader / writer and an eddy current is intentionally flowed. Thus, the communication defect between the reader / writer and the tag approaching this reader / writer is reduced.

An improved induction tool for formation resistivity evaluations. The tool provides electromagnetic transmitters and sensors suitable for transmitting and receiving magnetic fields in radial directions that are orthogonal to the tool's longitudinal axis with minimal susceptibility to errors associated with parasitic eddy currents induced in the metal components surrounding the transmitter and receiver coils. Various transmitter receiver combinations are provided to select sensitivity to a desired reservoir formation properties, for example, different orientations xy, xz, yz, 20-40, 20-90, and combinations, such as, Symmetric-symmetric; Asymmetric-symmetric; and Asymmetric-asymmetric. Measurements made with a multi-component logging instrument when used in a substantially horizontal, vertical or deviated borehole in earth formations are diagnostic of the direction of resistive beds relative to the position of the borehole.

An automatically adjusting magnetic resistance unit for an exercise device such as a bicycle trainer, in which the degree of resistance is automatically and non-linearly adjusted in relation to the rotational speed of a rotating member caused by the input of a user. The rotating member may be in the form of a flywheel having a number of supports extending between a hub and a rim. The supports define longitudinal grooves which slidably retain magnets that are biased inwardly toward the hub by biasing members. An electrically conductive member is located adjacent the flywheel. As the flywheel rotates in response to rotation of the bicycle wheel, the magnets interact with the conductive member to establish eddy currents that provide resistance to the rotation of the flywheel. The speed of rotation of the flywheel increases as the speed of rotation of the bicycle wheel increases, and centrifugal forces act on the magnets to cause the magnets to slide outwardly along the grooves in opposition to the bias of the biasing members. The outward movement of the magnets causes outward movement of the eddy current forces, to increase the resistance provided to rotation of the flywheel and the bicycle wheel. The variable resistance due to the increased or decreased rotational speed of the flywheel is smooth, based on the constant interaction of the counteracting forces of the biasing members and the centrifugal forces acting on the magnets.

Disclosed herein are apparatus and methods for measuring error associated with the rotation of bearings (50) used within a pointing device (11) on board a space-based platform. The apparatus includes inductive, or “eddy current,” proximity sensors (1000) adapted for measuring the positioning of bearing components. The apparatus also includes processing capabilities (1010) for receiving data from the proximity sensors (1000), and producing compensation data. The compensation data is used in one of various techniques for correcting errors in the angular measurement or pointing of the device (11). The techniques disclosed herein include conducting an initial calibration of the proximity sensors (1000) and generating calibration data. Once in active use, sensor measurements are combined with calibration data to produce compensation data. Ongoing measurements may be used to update the calibration data as necessary.

The present invention improves the cosmetic appearance of skin by controllably heating a superficial layer of skin thereby inducing acute tissue contraction or shrinkage and a wound response leading to the production of biomolecules, all of which result in improved cosmesis. The invention incorporates a source of radiofrequency electrical energy coupled to coil, with requisite impedance matching network, thereby resulting in the production of an alternating magnetic field. When tissue is brought into proximity of the alternating magnetic field, inductive heating of the tissue results as a consequence of either or both of dipole formation and oscillation, and eddy current formation. Optionally, cooling is provided to remove heat from the coil, the source of radiofrequency electrical energy, or the surface of the skin alone or in combination. The invention exhibits the significant benefits of, among other things, being non-invasive, not requiring electrical contact with the body of the subject, and providing controllable heating only to a thin layer of tissue.

An integrated current sensor includes a current conductor, a magnetic field transducer, and an electromagnetic shield. The magnetic field transducer includes a sensor die. The electromagnetic shield is disposed proximate to the sensor die. The electromagnetic shield has at least one feature selected to reduce an eddy current in the electromagnetic shield.

An apparatus having a plurality of coils (e.g., numerous thin-film coils formed in an array on a flex circuit), each coil acting as an excitation unit that generates an alternating excitation magnetic signal; and as a sensor configured to detect an eddy-current signal's phase and amplitude changes relative to the excitation magnetic signal. In some embodiments, the apparatus electronically scans a surface (e.g., of a metal plate) by successively switching to individual ones of the plurality of excitation / sensing coils (using, e.g., an analog multiplexer) without physical movement in order to detect anomalous signal changes in a manner that reduces signal changes due to probe lift-off relative to the surface. In some embodiments, the coils are placed across a large area of interest, for inspection of a large surface area in a few seconds without moving the apparatus. This can provide high-sensitivity detection and an accurate indication of flaw locations.

Placing inductors or resistors in parallel causes the combined value of inductance or resistance to decrease according to the parallel combination rule. This invention decreases the parasitic resistance of an inductor by placing several inductors in parallel. Furthermore, by careful placement of these inductors, the mutual inductance between these inductors can be used to increase the equivalent inductance value to a value near that of the original inductance value of a single inductor. Thus, it is possible to create an inductance with a much lower value of parasitic resistance. This invention allows the formation of high Q inductors and would be beneficial in any circuit design requiring inductances. Another aspect of this invention is that the coils can be partitioned to minimize eddy current losses. This invention can easily be implemented in a planar technology. Simulations of several tank circuits indicate that the power dissipation can be reduced 3 to 4 times when compared to conventional techniques.

A system for a baseband near field magnetic stripe data transmitter includes a mobile phone and a magnetic stripe transmission (MST) device. The mobile phone transmits a stream of pulses including magnetic stripe data of a payment card. The magnetic stripe transmission (MST) device includes a wave shaper, a driver and an induction device. The MST device receives the stream of pulses from the mobile phone, shapes and amplifies the received stream of pulses and generates and emits high energy magnetic pulses including the magnetic stripe data. The emitted high energy magnetic pulses are picked up remotely by a magnetic read head. The MST device shapes the stream of pulses to compensate for shielding, eddy current losses and limited inductance value of the magnetic read head.

A turbocharger includes a cylindrical wall and a non-ferromagnetic compressor wheel within the cylindrical wall. The non-ferromagnetic compressor wheel has fins. A magnetoresistive sensor housing is threaded through the cylindrical wall and houses a permanent magnet and at least one magnetoresistor. The permanent magnet is positioned so as to induce eddy currents on the fins. The permanent magnet magnetically biases the magnetoresistor, and the magnetoresistor senses rotation of the non-ferromagnetic compressor wheel.

An instrument pig and method of operation thereof for determining the characteristics of a ferromagnetic pipeline through which it passes, including a pig body, first and second coaxial circumferential, spaced apart magnets of opposed polarities supported to the pig body and providing substantially complete magnetic saturation of an area of the pipeline between the magnets, first instruments between the magnets and arranged to generate signals that are responsive to flux leakage servicing to provide first information as to anomalies in the pipeline interior and / or exterior surfaces, second instruments supported by the pig body between said magnets and arranged to generate signals that are responsive to eddy currents induced in the pipeline interior surface servicing to provide second information as to anomalies in the pipeline interior surface, signal processing circuitry combining the first and second signals and wherein the second instruments are energized only in response to signals generated by said signal processing circuitry.

Systems, apparatuses and methods are described for integrating an electronic metrology sensor with precision production equipment such as computer numerically controlled (CNC) machines. For example, a laser distance measuring sensor is used. Measurements are taken at a relatively high sample rate and converted into a format compatible with other data generated or accepted by the CNC machine. Measurements from the sensor are synchronized with the position of the arm of the machine such as through the use of offsets. Processing yields a detailed and highly accurate three-dimensional map of a workpiece in the machine. Applicable metrology instruments include other near continuously reading non-destructive characterization instruments such as contact and non-contact dimensional, eddy current, ultra-sound, and X-Ray Fluorescence (XRF) sensors. Various uses of measurements include: multiple component matching, correction of machine drift, closed loop control of machines, and verification of product tolerances via substantially complete serialized dimensional quality control.

A storage magnetic element, which minimizes the power loss in the planar winding due to the fringe magnetic field associated with a discrete air gap, is presented. The invention describes a construction technique wherein the magnetic core is formed by an E section made of high permeability magnetic material and an I section made by a material capable to store energy due to its distributed gap structure. The I section of the magnetic core in one of the embodiments is covered by an electrically conductive shied to force the magnetic flux into the I section and to minimize the component of the fringe magnetic field perpendicular on the planar winding. In another embodiment of this invention the electrically conductive shield is replaced by a high magnetic permeability material to accomplished the same goal of reducing the magnetic field component perpendicular on the planar winding. In a prefer embodiment of this invention the I section of the magnetic core has a cavity which will accommodate the middle leg of the E section. This construction will force the fringe magnetic field at the edge of the gap to be parallel with the planar winding of the storage magnetic element. In another embodiment of this invention a flat I section is used with the addition of another high permeability magnetic material placed on the I section on top of the winding. This construction will force the fringe magnetic field around the edge of the gap to be parallel with the planar winding. The embodiments of this invention are aimed at reducing the fringe magnetic field perpendicular on the planar winding, lowering the eddy current induced by this field.

In accordance with aspects of the present invention, a method of inspecting a well tubular is disclosed. The method utilizes a probe with a transmitter and detectors spaced from the transmitter by at least twice the diameter of the pipe to be tested. In some cases where multi-tubular structures are tested, the probe can include further detectors spaced from the transmitter by at least twice the diameter of the outer pipes as well. The phase of signals detected by the detectors relative to the transmitter are utilized to detect faults in the pipes.

The present invention is directed to configurations of eddy current probes and methods for using these probes to detect cracks initiating at the edge of holes in single-layered or multi-layered metallic structures. The new devices and methods are suitable to detect buried cracks around fastener holes located in layers of multi-layered structures, for example in airplane wing splices, containing fasteners disposed in rows. The probes include excitations coils and one or more magnetic sensors. The magnetic sensors can be arranged in absolute, differential or array configurations. The probe is scanned linearly along the fastener row. The invention also contains an apparatus or system for monitoring cracks around holes, including signal processing circuits, driving circuits, data acquisition and display, and scanning systems.