Showing papers on "Magnetic core published in 1987"

Inductive power coupling with constant voltage output

Abstract: A constant voltage inductive power coupling for magnetically transferring electrical power from a power source through an air gap to a load comprising a first electromagnetic inductor connected to a power source to generate a shaped alternating magnetic field, a said inductor with a saturable core separated by an air gap from the first inductor and magnetically coupled thereto to receive the shaped magnetic field, the core being responsive to the field to enter a state of magnetic saturation. A coil is electromagnetically coupled to the saturable core and has output leads connected to the load. A capacitor is in electrical communication with the coil to form a tuned circuit that is below resonance at the coupling operating frequency. The magnetic field induced by the first inductor to the second inductor causes voltage in the coil, whose magnitude is determined by the amount of magnetic flux in the core. The saturable core is responsive to any change in input voltage to magnetically counteract such change so as to maintain the core in its state of saturation thereby tending to keep the output voltage constant. Also any increase in load current is associated with a closer approach of the tuned circuit to a resonant condition tending to maintain the output voltage at a constant level. The invention is particularly useful in battery charging circuits or for other applications where the voltage required must be kept at a constant level.

A novel miniature planar inductor

Abstract: The conventional inductor consists of cores and wound wires, which are obstacles for the integration with other devices. The planar inductor, which has planar coils and magnetic layers in place of cores and wires, is fabricated on a substrate. Therefore it can be integrated with other devices, and it will be a fundamental element for the future magnetic IC. In this paper two kinds of planar inductors are described. One is the outer type, which has the larger inductance than any other planar inductor. The other is the inner type, which has the possibility for a variable inductor.

Autoregulating multi contact induction heater

Abstract: Contacts of a multipin connector may be soldered to leads of a board of the like by forming coatings of magnetic materials on each contact and locating the contacts between poles defined by an air gap of the magnetic core, each pole having a separate pair of opposed pole pieces disposed adjacent a pair of contacts whereby upon application of a constant a.c. current to a coil wound about the core the magnetic material is heated to a temperature approaching its Curie temperature whereby temperature regulation occurs.

Magnetic properties of fine iron particles

Abstract: Iron particles were prepared by a gas evaporation method in a nitrogen atmosphere. The particle size, shape, and magnetic properties were influenced by the nitrogen pressure. Particles prepared by this method were relatively stable in air and were not seriously oxidized. The recoilless fraction is low for the oxide layer, so that it cannot be detected at room temperature by Mossbauer spectrum. A superparamagnetic peak associated with the oxide microcrystal layer did not occur in the Mossbauer spectra due to the action of the magnetic field from the iron core and the interaction between iron particles and the low Debye temperature. From the electron micrography, the magnetic reversal process seems to be determined by a chain‐of‐spheres mechanism but Hc∼T curve cannot coincide with the Ms∼T curve at low temperatures. An increase of Hc may be associated with magnetic anisotropy. It is found that the magnetization versus temperature shows an anomalous increase in M(T) at higher T. We think that this means tha...

Current measuring and magnetic core compensating apparatus and method

Abstract: DC magnetic flux bias imposed on a magnetic core of a current transformer is compensated in response to an indication of the amplitude and duration of opposite polarity secondary winding current components. In a second embodiment, the magnetic bias is compensated by responding to the integral of the secondary current. The integral of the secondary current is a measure of the magnetic core flux variations. The durations of the positive and negative flux variations are compared.

Bi-directional drive motor system

Abstract: A bi-directional drive motor of the type having a force coil suspended in a magnetic field of a magnetic core assembly is provided. The force coil is made larger than the center pole piece which it surrounds so that the force coil is movable transverse to the length of the center pole piece as well as along its length to provide both X and Y directional movement. When two force coils are connected together on orthogonal axes and mounted in a common magnetic core assembly, X and Y directional movement is provided in a single drive motor system. When two drive motor systems are coupled to the same side of a top stage of a load platform, rotational or theta positioning is provided in addition to X and Y positional movement.

Device for measuring weak magnetic fluxes utilizing planar technology

Abstract: A device for measuring a weak magnetic field is disclosed. The device includes a substrate, a magnetic core having a high magnetic permeability and in the form of a surface film on a substrate, and at least two coils magnetically coupled to the magnetic core. A pulse generator is connected to one of the coils and is used to drive the magnetic core into intermittent saturation. The other coil is used to generate an output signal. The device can be used for measuring the weak magnetic fields associated with bank notes for identifying the values of the bank notes.

Power supply magnetic shunt for transmission line sensor module

Abstract: A self contained sensor module mounted on a power transmission line. The module is capable of measuring various parameters such as line current, voltage, conductor temperature and ambient temperature. The parameter values are processed by sensor electronics which digitize and periodically transmit the values to a ground receiver. The module power supply is coupled to the transmission line conductor by a transformer. The line conductor extends through a magnetic core in the module housing. A secondary shunt magnetic core is provided to limit induction of high voltages as a result of excess current flowing through the transmission line conductor.

Magnetic position sensor

Abstract: For displacement measurement, ie, the determination of the position of a measurement object (11) can be as a measurement target, a permanent magnet used, which is movable along a strip-shaped soft magnetic core (2) when the soft magnetic core (2) by two excitation coils (3, 4) in opposite directions is magnetized and located between the excitation coils (3, 4) a secondary coil (5). In this way, the position of a measurement object in a certain length range can accurately determine and easily.

Magnetic domains of permalloy films for magnetic recording thin film heads observed by spin-polarized SEM

Abstract: The domain structures of cores patterned in thin film heads for disk drive systems were investigated by using spin-polarized SEM. This method made it possible to determine the direction of the magnetization at the domains and domain walls in magnetic cores accurately. Domain structures in the track width, as small as 10 μ m could be observed. Domain structure could also be observed at the tapering area of a thin film head. It was found that the triangular domains without the closure domains are located at the edge of the magnetic core in single- and six-layered permalloy films in some cases. Such a domain structure was regarded as causing the wiggles in the read-out waveforms.

Magnetic head for perpendicular magnetic recording and reproduction

Abstract: A perpendicular magnetic head of high recording and reproducing efficiency which integrally incorporates a step-up transformer. A main pole for picking up a reproduce magnetic flux from a recording medium and applying recording magnetic field thereto is formed of a magnetic thin film. A signal winding formed of a thin film is disposed in the immediate vicinity of the forward end of the main pole so as to have a high conversion sensitivity per turn with respect to the reproduce magnetic flux from the recording medium. The signal winding which itself constitutes a closed circuit interlinks a magnetic path of the step-up transformer, thereby forming a primary winding of the transformer. A secondary winding from which head output is taken out is wound in the magnetic path of the transformer.

Issues related to 1–10 MHz transformer design

Abstract: Issues related to the design of high frequency transformers are discussed. An analysis of skin and proximity effects in the conductors and measurements of permeability and hysteresis loss in the magnetic material are combined in a computer assisted study of the relationships between size, efficiency, and frequency. Experimental data is presented for a prototype transformer.

Carrier for use in developing device of electrostatic latent image and production thereof

Abstract: The present invention provides a carrier coated by a polymer particle layer containing fine magnetic particles around a magnetic core, which may contain an electrical charge controlling agent, and the core may be pre-treated with a coupling reagent; the carrier gives excellent clearness to the copy and durability at repeating use.

PWM inverter controlled by a small saturable core

Abstract: A sinusoidal PWM inverter with MOSFETs controlled by an extremely small magnetic core is presented, which is simple and of high efficiency under high frequency switching. The circuit is based on the principle of the transistor core multivibrator. However the saturable core is used for PWM in the gate drive circuit. This inverter is especially suitable for small UPS system.

Floating-type magnetic head

Abstract: A floating-type magnetic head comprises a leading magnetic core, a trailing magnetic core, and a thin layer of a magnetic metal formed between the cores. A first magnetic gap is formed between the leading core and the thin film. A second magnetic gap is formed between the thin layer and the trailing core. The depth Gd of the end surface of the leading core is set to a value less than 10 microns. The depth h of the end surface of the trailing core is set to a value exceeding 100 microns.

Magnetic head having a stabilized zirconia slider

Abstract: A magnetic recording device comprises a magnetic disk having a magnetic recording layer formed on a substrate, a slider, a magnetic core attached to the slider, and a magnetic head adapted to be brought into contact with and separated from the surface of the magnetic disk. In this magnetic recording device, the magnetic recording layer of the magnetic disk is made of a Co-based alloy and the slider of the magnetic head has stabilized zirconia as the main phase thereof.

Structure of active type magnetic bearing

Abstract: An active type magnetic bearing for controllably supporting a rotatable shaft made of a magnetic material is constructed such that a stator made of an annular formed laminated iron core is provided around the rotatable shaft, a number of slots are formed along an internal surface of the iron core, stator windings of a number of phases are wound so as to be settled in the slots, thin sheet-like permanent magnets magnetized radially to provide a number of poles are secured onto the internal surface of the annular formed iron core with a predetermined air gap maintained between the permanent magnets and the rotatable shaft, and the stator windings of each phase are so wound that upon energization, a magnetic field thereby produced enhances a magnetic field produced by one of the permanent magnets while it reduces a magnetic field produced by another permanent magnet provided at a position 180° spaced apart from that one of the permanent magnets.

Floating type magnetic head

Abstract: PURPOSE:To improve recording and reproduction and to increase the density of the recording and reproduction by forming a magnetic gap which has specific narrow width and magnetic gap length by using a thin film or thin belt of a ferromagnetic metallic material with large saturated magnetic flux density or a thin film or thin belt of a ferromagnetic material alloy material. CONSTITUTION:A member 18 made of a nonmagnetic material with wear resistance is arranged in contact at the periphery of the thin film or thin belt of the ferromagnetic metallic material exposed in the surface of a magnetic gap part or its periphery or the thin film or thin belt 17 of the ferromagnetic alloy material. Further, the thin film or thin belt 17 contacts widely the main body part of a magnetic core made of the same magnetic ferrite material as the magnetic ferrite material which constitutes a slide part at the prolongation part of the central rail 12 of the slider part 10. This floating type magnetic head, therefore, has its magnetic gap (g) with specific narrow width and magnetic gap length constituted by the part of the thin film or thin belt 17 having large saturated magnetic flux density. Consequently, there is no fringe and no dummy gap is formed, so high-density recording and reproduction are realized.

Magnetic transducing head having clad core faces

Abstract: Magnetic transducing head comprising a magnetic core having two core limbs (1, 3) formed from a ferrite, a non-magnetizable gap (11) extending between two core faces (1B, 3B) of the core limbs and an electric coil (7) passing through a winding aperture (5). A cladding consisting of a first layer (13) of an Ni-Fe-based alloy is provided on at least one of the core faces, and a second layer (15) of an Fe-Si-Al-based alloy which is provided on the first layer.

Magnetic induction coupling system for contact-free transmission of a signal between at least two units

Abstract: It is intended to produce simple and reliable induction coupling between at least two units. Induction coupling arrangements (20, 40) are used, in the case of which in each case one induction coil (34; 50) is wound around a magnetic core (22, 42). The respective magnetic core consists of a centre core part (26; 46) which is formed cohesively with an outer circumferential core part (28, 48) over a base part. The respective magnetic core, which is thus constructed in the form of a pot, has an E-shaped cross-section. The induction coupling arrangements are preferably used for contact-free transmission of data signals and a supply voltage in a manufacturing automation system.

Method of constructing a magnetic core

Abstract: A method of constructing a magnetic core for electrical inductive apparatus, such as transformers and reactors, having stepped-lap joints between adjoining leg and yoke portions thereof. The method provides a continuous stepped-lap joint which extends around each corner of the magnetic core, while incrementally clipping only one end of each leg and yoke lamination, and the laminations are assembled without any portion thereof protruding past the major outline of the magnetic core configuration.

Magnetic core and manufacture thereof

Abstract: PURPOSE:To obtain a magnetic core having low core loss, high permeability and small characteristic deterioration due to strain, etc., by winding or laminat ing a sheet metal consisting of an Fe base soft magnetic alloy, which has a composition represented by specific general formula and the greater part of texture of which are composed of fine crystal grains, or attaching the sheet metal onto a substrate and forming the magnetic core. CONSTITUTION:A sheet metal made up of an Fe base soft magnetic alloy, which has a composition represented by general formula (Fe1-aMa)-100-X-Y-Z-alpha-beta-gammaCuXSiYBZM'alphaM''betaXgamma(atomic %), at least 50% of texture of which is composed of fine crystal grains and crystal grains of which have mean grain size of 500Angstrom or less when crystal grains are measured in maximum size, is wound or laminated, or attached onto a substrate, thus shaping a mag netic core. Where M in formula represents one kind or more of Co and/or Ni, M' one kind or more of Nb, W, Ta, Zr, Hf, Ti and Mo, M'', one kind or more of V, Cr, Mn, Al, platinum group elements, Sc, Y, rare earth elements, Au, Zn, Sn and Re and X one kind or more of C, Ge, P, Ga, Sb, In, Be and As. X-Z and alpha-gamma respectively satisfy specified conditions.

Method and apparatus using a stationary magnetic body for effecting signal transfers between a moving magnetic core and a magnetic storage medium

Abstract: Magnetic transducer-keeper combination embodiments of the invention are described. Each has a magnetic core defining a physical gap and a thin magnetic keeper arranged in close proximity of the core to bridge the gap. A magnetic flux from the gap saturates the keeper inan area bridging the gap, thereby forming a signal transducing zone in the keeper. The keeper is maintained stationary and the core moved or scanned with respect to the same, thereby moving or scanning the transducing zone in the keeper.

Floating magnetic head having a magnetic core buried in a channel on an air bearing rail

Abstract: A core burying channel is formed on the outer side surface of an air bearing rail of a floating magnetic head floating on a magnetic disk by an air-flow in a direction perpendicular to a magnetic recording medium travelling direction, and a magnetic core is buried in this core burying channel. This magnetic head can be produced easily by a production method which forms a core burying channel in a non-magnetic block, then deposits a magnetic material to the core burying channel and removes unnecessary portions of the magnetic material.

Transformer Applications of Amorphous Alloys in Power Distribution Systems

Abstract: The need for more efficient transformer core materials, due to increased recognition by electric utilities of the costs of system losses, has spurred the development of amorphous alloy usage in power transmission and distribution transformers. Amorphous alloy core fabrication, as it relates to single-phase distribution transformer operating characteristics, is discussed. The effects of winding tension, a superior core annealing technique, and other annealing parameters are included. The potential use of Powercore??? consolidated amorphous alloy strip in three-phase stacked core transformers is also discussed in terms of the magnetic and physical characteristics of this newly developed amorphous core material. The most recent data on the thermal stability of amorphous core alloy magnetic properties are also summarized. These data confirm that core loss degradation is not expected to occur under typical transformer operating conditions and life.

Stationary induction apparatus

Abstract: PURPOSE: To obtain a small-sized stationary induction apparatus which is little deteriorated in its characteristics and exerts small magnetic effects on its periphery, by burying coils into resin with a dispersed ferromagnetic material and molding this resin to form an iron core. CONSTITUTION: Coils provided with windings 11, 12 so as to form an opening along a central axis are buried into a base material 16, having an insulating property, such as resin with ferromagnetic material powder dispersed therein, and the base material 16 with the ferromagnetic material powder dispersed therein is molded into a desired shape, so that the base material, with which an opening part 14 is filled, functions as an iron core with windings provided therearound. The base material 16 put in the ferromagnetic material powder having the insulating property, in this iron core, functions to reduce an eddy current. Since the coils 15 are also surrounded with the base material 16, corresponding to the iron core, with the ferromagnetic material dispersed therearound, a magnetic circuit passing gaplessly through the opening in the center of the coils 15 is formed around the coils 15. Hence, almost no flux leaks outside and so magnetic effects exerted on the outside can be reduced. COPYRIGHT: (C)1988,JPO&Japio

Arrangement for the contactless measuring of an electric current in a conductor

Abstract: In an arrangement for the contactless measuring of the electric current in a conductor (1) in which a magnetic core (3) enclosing the conductor exhibits a gap in which a magnetic field sensor (5) is arranged, the pole face of the magnetic core essentially corresponds to the active surface of the magnetic field sensor. In this arrangement, the cross sectional area of the magnetic core can preferably become greater with increasing distance from the gap.

High frequency transformer

Abstract: PURPOSE: To provide a structure, in which gas is not ionized, and to prevent decrease in reliability due to ionized gaseous molecules, by filling paths of intense magnetic flux with filler so that ionized gas is not formed at gap parts of transformer cores, and removing gas. CONSTITUTION: When E-E type cores are used, a light emitting phenomenon occurs at a gap part A, where the central legs of leg cores 5 of the E type face to each other. This phenomenon becomes intense when electric power, which is transmitted from the primary side to the secondary side of the transformer, is increased. Even if a spacer made of an insulator is inserted between, e.g., the first magnetic core and the second magnetic core, the light is emitted from the surrounding part of the spacer. Therefore, it is necessary to input a filler into a part including said light emitting part and into a bobbin so as to remove air. The light emitting part is filled with silicone rubber 1 so as to prevent the light emitting phenomenon due to ionization that is yielded in this way. Thus the reliability of a high frequency transformer for a switching power source rated at high power is improved, and a more compact high frequency transformer can be adopted. COPYRIGHT: (C)1988,JPO&Japio

FEM analysis of 3D eddy current field in power transformer

Abstract: The three dimensional finite element analysis of eddy current problems using the complex magnetic vector potential is applied to a practical three phase power transformer. The eddy current densities in the oil tank and other steel structure parts and the magnetic flux densities in the whole transformer are computed. Several methods to reduce the amount of computation are presented. The eddy current losses in steel materials are computed by combining numerical method with analytical. The computed results are in substantial agreement with the corresponding experimental values.