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Magnetics in Japan, IEEE Translation Journal on

Issue 6 • Date Nov.-Dec. 1994

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Displaying Results 1 - 25 of 63
  • [Front cover]

    Publication Year: 1994 , Page(s): c1
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  • List of contributors

    Publication Year: 1994 , Page(s): nil1
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  • [Breaker page]

    Publication Year: 1994 , Page(s): nil1
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  • Table of contents

    Publication Year: 1994 , Page(s): 1 - 4
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  • Opinion

    Publication Year: 1994 , Page(s): 5
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  • Opinion

    Publication Year: 1994 , Page(s): 6
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  • Magneto-Impedance Element Using Amorphous Micro Wire

    Publication Year: 1994 , Page(s): 7 - 14
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    A large magneto-impedance (MI) effect was found in amorphous magnetic wires while passing a high-frequency current. The amplitude of the induced voltage between the ends of a wire changes by 40 to 50% when an external magnetic field of about 10 Oe (approximately 800 A/m) is applied parallel to the wire axis. This paper reports the principles and basic properties of the MI effect in very small amorphous wires of composition (Fe0.06Co0.94)72.5Si12.5B15 and magnetostriction ¿10¿7, and describes an application to rotary encoder heads using very small MI elements 30 ¿m in diameter and 1 mm in length. View full abstract»

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  • Distance Sensors Using Domain Wall Propagation Driven by a Wire Current Pulse Train in Amorphous Magnetostrictive Wires

    Publication Year: 1994 , Page(s): 15 - 20
    Cited by:  Patents (1)
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    A new distance sensor described in this paper uses stepwise propagation of a domain wall by a pulse wire current train in a twisted magnetostrictive amorphous wire. A distance sensor of simple construction and with a length of 1000 mm was obtained. The sensor characteristics are controlled by applying torsion, and a suitable amount of torsion, with minimal nonlinearity, was identified. To improve the resolution of the sensor while preserving the good linearity, we tried changing the pulse shape of the driving current by adding a bias current to the pulse train current. A digital type distance sensor with a resolution of about 1 mm and nonlinearity of about 1% over the length of the 1000 mm long wire was achieved. View full abstract»

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  • Examination of the Shape Variation and Stress Distribution of Vibration Elements Using Giant Magnetostrictive Material

    Publication Year: 1994 , Page(s): 21 - 26
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    Acoustic vibration elements using giant magnetostrictive material (AVEG) are employed as vibration sources for under-sea acoustic propagation over distances of 1000 km or more. In this paper the magnetic circuit of the driving unit was analyzed using the finite element method. The flux density distribution is nonuniform in the magnetostrictive vibrator. Converting flux density B into magnetostriction ¿, we examine the difference in the shape variation and stress distribution of the magnetostrictive vibrator. We also show the influence on magnetic coupling of magnetostrictive vibrators that are constructed with eight pieces of the AVEG arranged octagonally. View full abstract»

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  • Fabrication of Thin-Film Actuators Using Magnetostriction

    Publication Year: 1994 , Page(s): 27 - 32
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    We fabricated two kinds of cantilever actuator and a traveling machine by using magnetostrictive Tb-Fe and Sm-Fe thin films on a polyimide substrate. No power supply cable is required for their actuation, because they are driven by an external magnetic field. The magnetostrictive cantilevers exhibited a large deflection in low magnetic fields. Their unique characteristics suggest that magnetostriction can be used as the driving mechanism of microactuators. View full abstract»

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  • Fundamental Characteristics of a Large-Scale Cylindrical Magnetic Shield with Shaking

    Publication Year: 1994 , Page(s): 33 - 38
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    A large-scale cylindrical magnetic shielding case was developed. It was made of permalloy (outer diameter 68 cm, length 180 cm, thickness 1.6 mm, weight approximately 60 kg) with an opening at one end and with Metglas® 2705M amorphous ribbons (width 5 cm, thickness approximately 22 ¿m) wound spirally about the permalloy case in 16 layers (total weight 12.1 kg) to cover the surface. A toroidal coil (36 turns) was wound around the amorphous layers to allow the creation of a magnetic shaking field. An external magnetic field was applied to the shielding case by means of a large rectangular Hemholtz coil, to evaluate the shielding factor, which was about 2700 at a frequency of 0.5 Hz when the shaking frequency was 200 Hz. At higher frequencies, it gradually dropped. The shielding factor was almost constant relative to the amplitude of the disturbing field down to 3 mG; beyond that point, a residual field could not be detected because of the limit of resolution of the flux gate magnetometer used. The leakage of the shaking field was about 30 ¿G at the center of the shielding case. View full abstract»

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  • Permeability and α-Fe Phase Precipitated in Fe-Si-B-Cu-Nb Amorphous Alloys

    Publication Year: 1994 , Page(s): 39 - 46
    Cited by:  Patents (2)
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    The soft magnetic properties of amorphous Fe-Si-B-Cu-Nb alloys are markedly improved by annealing the alloys above the crystallization temperature. The magnetic permeability of the annealed Fe74SixB22-xCu1Nb3 alloys shows a maximum value at an Si concentration of x=14. The precipitation of μ-Fe grains is observed for the annealing temperature giving the highest magnetic permeability. The lattice constant of the α-Fe phase shows a minimum at the annealing temperature yielding the highest magnetic permeability, and depends strongly on the Si concentration. The Si content in the μ-Fe phase estimated from the lattice constant is about 20 at% for Si concentrations above x=12. The volume fraction of the precipitated μ-Fe phase depends on the B concentration in the amorphous alloy. The grain size of μ-Fe at the optimum annealing temperature is about 130Å. To explain the mechanism of the high permeability, it is necessary to consider factors other than the grain size the volume fraction of the precipitated μ-Fe. View full abstract»

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  • Magnetic Properties of Extruded Nanocrystalline Fe-Nb-B Alloys

    Publication Year: 1994 , Page(s): 47 - 54
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    A bulk Fe84Nb7B9 alloy was produced by extruding amorphous powder at temperatures (Te) between 653 and 723K, at pressures (Pe) between 824 and 1208 MPa, and at a speed (Ve) of 5 mm/s. The subsequent annealing of the extruded bulk alloy for 3.6 ks at temperatures between 873 and 973K resulted in the formation of a (for the most part) single bec phase, with grain sizes near 10 nm. The bulk alloy, extruded at a Pe above 1000 MPa, has a high relative density of 99%. The soft magnetic properties are better for bulk materials extruded at lower pressures, and the bulk alloy extruded at Te=698K and Pe=870 MPa exhibits a magnetization (B800) of 1.40 T, a permeability of 1123, and a coercive force (Hc) of 47 A/m, values which are inferior to those of the bec ribbon alloy (1.49 T, 22000, 8 A/m). The difference between the soft magnetic properties of the bulk material and the ribbon forms is presumably due to the inhomogeneity of the microstructure, oxidation of the powder, and the remainder of a higher internal stress in the bulk alloy. View full abstract»

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  • Magnetostriction of Fe-Co Alloy Films and Its Control by Multilayering

    Publication Year: 1994 , Page(s): 55 - 60
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    The bec Fe70Co30 alloy has a high saturation magnetization and a large positive magnetostriction, whereas the fcc Ni75Co25 alloy has a large negative magnetostriction value. This paper reports the results of a systematic investigation into the magnetic properties of FeCo/NiCo multilayer films. Magnetostriction in an FeCo/NiCo film becomes smaller as the ratio of the thickness of the NiCo layer to that of the FeCo/NiCo film increases. The film (3/7 nm) has a saturation magnetization of 120 emu/g and a coercivity of 1.7 Oe, with nearly zero magnetostriction. View full abstract»

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  • Phase Modulation Device Using Amorphous Short Wire

    Publication Year: 1994 , Page(s): 61 - 65
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    A new phase-modulation device with simple structure and high reliability was constructed using a short amorphous wire. A high-frequency ac current (carrier) and a signal current are simultaneously passed through the wire, which undergoes the large Barkhausen effect when the circumferential flux changes. Highly linear modulation characteristics were obtained up to 0.67¿ using a triangular-wave ac current, passed through tension-annealed wire 30 ¿m in diameter and 5 mm in length. This simple yet reliable phase modulation device is expected to find applications in the field of factory automation communication networks. View full abstract»

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  • A Technique for Measuring Thin-Film Inductors Driven at High Flux Densities

    Publication Year: 1994 , Page(s): 66 - 71
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    This paper discusses the basic properties of thin-film inductors driven at high flux densities. We made inner-coil-type thin-film inductors, each with either a closed or an open magnetic circuit, and developed a technique for measuring the impedance of the inductors at high flux densities. We used this technique to reduce the multiple voltage reflections between amplifier and inductor. The impedance of the magnetic thin-film inductors varied according to the magnetic field intensity, because of flux saturation. View full abstract»

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  • Analysis of Magnetic Shielding Effects for Thin-Film Inductors

    Publication Year: 1994 , Page(s): 72 - 77
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    Issues related to magnetic shielding effects are discussed for inner-coil type thin-film inductors with closed magnetic circuits. The relationship between magnetic shielding effects, mutual inductance, and proximity effects are investigated using the finite integral equation method. The results show that obvious shielding effects occur in the inductors and that the mutual inductance is not influenced by the shielding effects. View full abstract»

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  • Application to an EMI Noise Filter of a High-Loss CoZrNb/SiO2 Multilayer Film

    Publication Year: 1994 , Page(s): 78 - 83
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    This paper reports the application of a magnetic alloy/nonmagnetic insulator multilayer film in EMI noise filters. The eddy-current skin effect in the magnetic alloy layers was used to achieve high-loss properties. The thickness of each layer and magnetic anisotropy of a CoZrNb/SiO2 multilayer film were designed such that the film would exhibit high-loss properties in the 30 to 1000 MHz frequency range. A noise filter tube was constructed incorporating such high-loss film, and a large impedance and noise attenuation for common-mode noise in this frequency range were confirmed. A noise filter tube was constructed with size reduced by a factor of ~100 compared with a conventional filter (ferrite core). View full abstract»

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  • Characteristics of a DC-DC Converter Using a Thin Film Microtransformer and a Microinductor

    Publication Year: 1994 , Page(s): 84 - 89
    Cited by:  Papers (1)  |  Patents (1)
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    A thin-film microtransformer and a microinductor were fabricated, using photolithographic techniques for all processes. The microtransformer and microinductor are the same size, 3.5×3.9×0.06 mm3, and both have a layered structure with circular spiral windings between the upper and lower CoFeSiB films. The microtransformer and microinductor were mounted on a primary controlled forward converter, and the converter was operated at high frequencies between 6 and 10 MHz with a load resistance of 51 ¿; an output voltage of 1.9 V was obtained for an input voltage of 6 V. This result is important as a first step toward developing a microconverter in which transformers, inductors, capacitors, and rectifier diodes are integrated monolithically. View full abstract»

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  • Acute Animal Experiment Using a Linear Motor-Driven Total Artificial Heart

    Publication Year: 1994 , Page(s): 90 - 97
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    A linear pulse motor developed by the authors was selected as the actuator for a total artificial heart, because it had the highest thrust/volume ratio, at 0.76 N/ml, of the eight kinds of linear motor considered. This paper summarizes the results of an acute animal experiment using a linear pulse motor-driven total artificial heart (linear TAH). The linear TAH consisted of a linear pulse motor, two sac type blood pumps, and four artificial valves. The mass was 1.3 kg and the volume was 540 ml. The volume of the TAH was a little larger than the target size, equal to the volume of an adult human's fist. The linear TAH was attached to a sheep of body weight 42 kg to evaluate its hemodynamic performance. The descending aortic flow rate was 1.5 1/min, equal to 50% of the rate in the control data. The difference between the flow rates of the left and right blood pumps was 12 to 13%, when the left atrium pressure reading indicated normal pressure. The sheep was sacrificed two hours after the operation. The data obtained suggest that the linear TAH can be used as a circulation-supporting device that satisfies clinical circulatory requirements. View full abstract»

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  • Performance Evaluation of a Linear Pulse Motor-Driven Intra-Aortic Balloon Pump

    Publication Year: 1994 , Page(s): 98 - 103
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    An intra-aortic balloon pump (IABP) is an effective device for supporting circulation in the event of acute heart failure. Small IABP devices are in urgent demand in medical fields. The authors have investigated an IABP device which uses a linear pulse motor (LPM) in order to reduce the device size. This paper discusses the characteristics of the LPM developed by the authors to drive the IABP, and describes the results of evaluation of an LPM-driven IABP. Our investigation revealed the following. (1) The trial LPM was 1.3 L in volume and had a mass of 6.3 kg. Its use will reduce the weight of IABP devices. (2) The LPM has a high thrust/volume ratio of 0.88 N/ml. (3) The driving characteristic of the LPM-driven IABP was evaluated using a mock testing device. The maximum pumping rate of this IABP device is approximately 120 beats/min. As a result, an LPM-driven IABP will be capable of sufficiently high performance to enable clinical use. View full abstract»

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  • Evaluation of the Thrust Constant of a Linear DC Motor for a Pen Recorder

    Publication Year: 1994 , Page(s): 104 - 109
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    Pen recorders with moving-coil-type linear dc motors (LDMs) have already been used in practical applications. However, an optimal design has not yet been established within the dimensional limitations of such devices. This paper provides a guideline for optimum design through characteristic analysis of pen recorder units, using a thin, long-stroke LDM. In the LDM, the flux density acting on the coil is equal to the flux density in the gap. The LDM thrust constant consists of N, 1 and B, where N and 1 are known as design values. However, B is determined by the magnetic design. The finite element method (FEM) is used to analyze the three-dimensional magnetic fields of the magnetic circuit, which consists of a permanent magnet and yokes. View full abstract»

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  • Effects of Cores on the Characteristics of an Induction VCM

    Publication Year: 1994 , Page(s): 110 - 116
    Cited by:  Papers (1)
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    An induction voice coil motor (VCM) is composed of a moving metal ring, permanent magnets, cores and exciting coils. The moving ring current induced by an exciting coil current, and the magnetic flux of the permanent magnets, generate a driving force acting on the moving ring. The induction VCM is not able to generate forces below the lower cutoff frequency or above the higher cutoff frequency. The lower cutoff frequency is lowered by raising the permeability and lowering the hysteresis loss of the core; the higher cutoff frequency is raised by reducing core eddy current losses and lowering the leakage inductance of the moving ring. There is an electromechanical parallel resonance near the lower cutoff frequency, and the higher permeability and lower loss make the resonance stronger and lowers the resonance frequency. View full abstract»

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  • Static Thrust Improvement of a Linear Proportional Solenoid

    Publication Year: 1994 , Page(s): 117 - 121
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    A linear proportional solenoid (LPS) is an actuator for a proportional control valve used in hydraulic pressure-control devices. The LPS thrust must be constant over a specified displacement range, and must be proportional to the current. This paper describes simulations of the thrust-displacement characteristics of LPSes as determined by FEM, conducted with the aim of improving the LPM thrust. In model P, where high flux-density permendur was used in the LPS stator and mover, the maximum thrust increased from 27 to 40 N. The range of constant thrust, however, decreased from 1.0 to 0.5 mm. In model S, where permendur was used in the stator and mover, and the salient pole of the stator in the LPS was modified, the range of constant thrust was the same as in the present model. Moreover, the static thrust in the range of constant thrust increased from 27 to 38 N. View full abstract»

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  • Performance Analysis of a Linear Oscillatory Actuator for a Milking Unit

    Publication Year: 1994 , Page(s): 122 - 126
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    Milking with a conventional milking machine often involves teat trouble, because the pulsation rate of the milking is not variable. A new cylindrical linear oscillatory actuator (CLOA) developed by the authors has a freely variable pulsation rate. This paper analyzes the static and kinetic thrusts of the CLOA. The mover of the CLOA is capable of oscillation at a frequency of 1 Hz with a stroke of ±2 mm, and will be used in new milking machines. View full abstract»

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Aims & Scope

IEEE Translation Journal on Magnetics in Japan is a publication of the IEEE Magnetics Society published between 1985 and 1994.

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Meet Our Editors

Editor-in-Chief
James E. Opfer
Hewlett-Packard