Showing papers on "Magneto published in 1998"

Generating apparatus including magneto acting as power supply

Abstract: A generating apparatus for feeding a current to a battery using a magneto as a power supply is disclosed which is capable of varying a magnetic field acting on generating coils to widely control characteristics of the magneto. A rectifying/switch circuit is arranged between the magneto and a load, which incorporates the battery. The rectifying/switch circuit includes diodes and switch elements. The diodes are 2n (n≧2) in number and are bridge-connected to each other. The switch elements are connected to the diodes by reverse parallel connection. A switch control unit applies an AC control voltage of a predetermined phase from the battery through the rectifying/switch circuit to the generating coils, so that a phase of the AC control voltage may be varied to widely vary characteristics of the magneto.

A method to eliminate birefringence of a magneto-optic AC current transducer with glass ring sensor head

Abstract: This paper reports a novel method of assembling a magneto-optical current transducer, which can eliminate both thermal transient and construction-caused birefringence to a large extent. The method is simple and practical, and needs no temperature compensation in signal processing. With a closed aluminum shell, sensing material buffers and flexible construction, the accuracy of the compromise-developed MOCT with glass ring sensor head was better than 0.3% over a temperature range of -30 to 70/spl deg/C and current range from 100 to 2400 A. The field testing verified this performance.

Engine management system

Abstract: An engine management system for 4-cycle engines includes a processing means and utilizes various inputs from sensors operatively connected to the engine for the purpose of providing the correct fuel/air ratio or spark ignition angle for the engine in a manner whereby the transient response is fast. The engine management system utilizes the rotational speed information that is obtained from a magneto or speed sensor to determine the speed of each engine revolution. The system effectively solves many of the fuel/air ratio problems that are caused by load transients occurring on the engine. By comparing such high pass filtered speeds of selected revolutions, the system is able to determine the inferred engine intake air flow. By using measured system rotational inertia compensation factors for the engine together with the inferred intake air flow, the system can accurately determine the amount of fuel to be fed to the engine for proper operation.

Rotational speed device with magneto-electric elements

Abstract: A rotational speed-detecting device of the present invention drives a sensor means 11, which includes a detecting unit that connects magneto-electric elements in series. A comparison voltage generator connects comparison voltage resistors in series, and is connected in parallel with the detecting unit, with a constant voltage by a constant-voltage control means 13, to which constant voltage is supplied by a constant-voltage generating means 14. The constant voltage means 14 controls a constant current of the constant-current means 15 with an on-and-off output from a comparison means 12 so as to superpose and flow a rectangular wave current in a power supply line between Vcc and VR.

Magnetic field sensor with colossal magneto-resistive material contained within the coil of an oscillator

Abstract: Sensors, systems and methods for measuring magnetic field strengths in both AC and DC magnetic fields by using CMR material in tunable, radio-frequency LC oscillators are disclosed.

Electronic magneto-resistive memory cell of Magnetic RAM type has magnetic sensor element in form of AMR or GMR (Giant-Magneto-resistance), enabling more compact data densities to be achieved

Abstract: Component comprises a magneto-resistive element (10) that functions as sensor and a second magneto-resistive element (1) that functions as a storage element. The sensor element is in the form of an AMR or GMR (Giant-Magneto-resistance). The storage element is in the form of MRAM cell. (Magnetic random access memory).

Magneto-optical properties of one-dimensional magneto-photonic crystals

Abstract: Recently, we have shown theoretically that a large enhancement in magneto-optical (MO) Faraday effect takes place in bi-gyrotropic magnetic films with disordered multilayer structures:'.' the films of interest are composed of Bi-substituted yttrium iron garnet (Bi:YIG) layers and SiO, layers which are piled up in a disordered sequence. The enlargement of the MO effect is strengthened remarkably by choosing appropriate film structures for supporting the localization of light within the films. In this paper, we show a huge MO effect arises when the film structure meets the socalled one-dimensional (magneto-)photonic crystal with a defect,' in which a Bi:YIG thin layer is sandwiched between two (Bi:YAG/SiO,) X k and (Si0JBi:YIG)x k reflection layers. For instance, the one-dimensional magneto-photonic crystal exhibits BF (Faraday rotation angle) 30 degl p m at h (wavelength of light) = 1.15 pm, the value of which is about 300 times larger than that of Bi:YIG single-layer film (BF=O.l deglpm). The unique MO effect of the one-dimensional magneto-photonic crystals was investigated in detail, for elucidating the huge enhancement of OF and for clarifying the design conditions of the media. It was found that the large 8~ of the medium originates from a slight difference in the localization conditions for two eigenmodes of lights in the Bi:YIG layers (tight-hand and left-hand circularly polarized lights). Then, provided that these eigenmodes of lights are strongly localized almost simultaneously, the onedimensional magneto-photonic crystal exhibits a considerably high MO effect with a high transmissivity. This situation can be realized when the structure of one-dimensional magneto-photonic crystal fulfills following conditions: n,d,=n,d,=h/4 and n , D M = m h / 2 with m=0.1,2;. . , where n, and n,? are, respectively, refraction constants of Bi:YIG and SiOz layers, while d , , d , , and DM are, respectively, thicknesses of Bi:YIG and SiO, reflection layers, and the center Bi:YIG layer.

Rotational position sensor employing magneto resistors

Abstract: A rotational position sensor assembly (10) includes a wheel (20) having a ferromagnetic hub portion (22) and a resistor support member (24) on which an array of magneto resistor elements (28) are mounted. Surrounding the wheel (20) and rotatable relative to it is a magnetic return element (12) on which are mounted permanent magnets (18). The magnetic field created is tangential to the particular MR element(s) (28) aligned with this field, causing a change in resistance that indicates the relative rotational position of the magnetic return element (12) relative to the wheel (20).

Metallic and non-metallic particle sorting process comprises passing the particles through an alternating magnetic field to produce vortex streams which weaken the field and are detected by magneto-resistive sensors.

Abstract: Magneto-resistive sensors are used to sort metallic and non-metallic particles by a process which comprises passing the particles through an alternating magnetic field with a frequency range 0.1-1.0 MHz, to produce vortex streams. The latter weaken the field and this is detected by the sensors and transformed into electrical signals, which are rectified, amplified and evaluated.

Analysis of magneto-mechanical stability of iter magnet

Abstract: The magneto-mechanical interaction of the magnet system elements can be the cause of buckling. While the elastic internal forces are stabilizing ones, the magnet forces can be stabilizing or destabilizing depending on the magnet system configuration and current directions. Problems of toroidal field coils and poloidal field coils stability are considered and stability conditions are obtained.

Magnetoresistive effect magnetic head

Abstract: PROBLEM TO BE SOLVED: To provide a magnetoresistive effect magnetic head without a Barkhousen noise and improving the soft magnetic characteristic of a magneto resistive effect film by making the ferromagnetic film a laminated film between a film having negative or zero magnetostriction and a film having positive or zero magntostriction, and making the absolute value of the magnetostriction of the ferromagnetic film a specified value or below in the magnetoresistive effect film of a spin valve structure. SOLUTION: The magneto resistive effect film 20 of the spin valve structure is constituted of a first ferromgnetic film 21, a non-magnetic conductive film 22, a second ferromagnetic film 23 and an anti-ferromagnetic film 24. The intrasurface magnetization of the first ferromagnetic film 21 and second ferromagnetic film 23 are turned in the directions tilting by 90 deg. to each other in the state that an external magnetic field isn't applied. The magnetization of the first ferromagnetic film 21 is rotated freely, and thus, a resistance change occurs, and an output is generated. Then, the first ferromagnetic film 21 consists of a third ferromagnetic film 25 having the negative or zero magnetostriction and a fourth ferromagnetic film 26 having the positive or zero magnetostriction. Then, the absolute value of the magnetostriction of the first ferromagnetic film is required to be 4×10 or below.

Properties of Elastically Coupled Magneto-Electric Elements

Abstract: Magneto-electric (ME) elements were constructed by combining piezoelectric materials and magnetostrictive films. The fundamental properties of elements were studied, to determine whether the elements exhibit any considerable ME effect at room temperature. The elements had a hybrid structure, in which thin soft glass substrates with highly magnetostrictive amorphous FeCoSiB films were bonded on PZT piezoelectric substrates. When a dc voltage was applied to an element, large changes in the magnetic properties of the FeCoSiB film were observed: for example, when a dc voltage of between -200 V and +200 V was applied, the change in magnetic permeability of the film reached more than 1680%. These unique characteristics of the present ME elements are considered to be very attractive for constructing novel types of micromagnetic devices.

Universal isomorphism magnetic field sensor

Abstract: The utility model relates to a sensing device for measuring the value of a magnetic field, particularly a universal isomorphism magnetic field sensor formed by the magnetoresistance effect of magnetic particle sheet bands or thin film materials The purpose of the utility model is that when the magnetic field of certain point of space is rapidly and accurately measured, the adjustment of measurement direction does not need to consider The utility model provides a magneto resistor as a sensitive element, and the magneto resistor is formed by the isotropic magnetic effect of the magnetic particle sheet bands or the thin film materials and is connected with a power supply The magneto resistor is connected with a standard resistance to form an electrical bridge and then is connected with a differential amplifier to form the universal isomorphism magnetic field sensor

Device for remote determination of position of object ( versions )

Abstract: FIELD: measurement technology, aids measuring coordinates, speed and angular values of object in automatic control systems, in geomagnetic navigation, in precision mechanical and instrumentation engineering. SUBSTANCE: in compliance with first and second versions device for remote determination of position of object has three-component magneto sensitive sensor, nine amplification-conversion units, three-component source of alternating magnetic fields made of three inductance coils with mutually orthogonal axes and generator of alternating voltages interconnected in certain manner. It provides for determination of coordinates and angular position of object in known octant within limits from 0 to 360 deg while object rotates about axis chosen at will. In agreement with third version device for remote determination of position of object includes three three-component magneto sensitive sensors, twenty seven amplification-conversion units, three-component source of alternating magnetic fields placed on object and made from three inductance coils with mutually orthogonal axes and generator of alternating voltage interconnected in certain manner. It provides for determination of coordinates and angular position of object within limits from 0 to 360 deg while object rotates about axis chosen at will. In accordance with fourth version device incorporates four three-component magneto sensitive sensors, commutator, eighteen amplification-conversion units, two three-component sources of alternating magnetic fields each composed of three inductance coils with mutually orthogonal axes and generator of alternating voltages interconnected in certain manner. It provides for determination of coordinates and angular position of object within limits from 0 to 360 deg while object rotates about axis chosen at will and in absence of contact of sensors, commutator and amplification-conversion units with inductance coils and generator of alternating voltages located on object. EFFECT: expanded application field, enhanced functional reli

Limdow media with magneto static coupling msr function

Abstract: We have developed the large capacity Light Intensity Modulation Direct Over Write (LIMDOW) Magneto Optical (MO)media by adding the Magnetically induced Super Resolution (MSR) function to the conventional LIMDOW. We selected the magneto static coupling Center Aperture Detection (CAD) from the various kinds of MSR because of its good suitability to the conventional LIMDOW. This newly developed CAD-LIMDOW realizes high performance of both MSR and DOW function. The recording density of 2.7Gbit/inch2 has been obtained with sufficient power margin by using a land/groove substrate at the condition of 680nm wavelength LD and NA=0.55. It means that 3.5Gbit/inch2 density is probable by using the optical head with wavelength of 650nm and NA=0.6.

Bias Voltage and Temperature Dependence of Magneto-Tunneling

Abstract: The large magnetoresistance in spin dependent tunneling (SDT) junctions has great device potential. One of the puzzling features of SDT is its strong dependence of MR on bias voltage.' We have studied a variety of junctions and have observed a correlation between this voltage dependence and the non-linearity of the I-V characteristic. Since trap states in tunneling barriers can lead to such non-linear behavior, we have developed a model based on the assumption of traps which provide a second, spin-independent, channel for tunneling, in addition to the spin-dependent direct tunneling channel. Such traps in our case might arise from nonuniformity oxidized aluminum or impurities. The ratio of the two currents, which depends on the trap state density, determines the magnetoresistance ratio. The model predicts that the spin independent current is largely responsible for the non-linearity of the I-V curve. The relative contribution of the spin independent current increases as bias voltage increases, resulting in a MR decrease. A slower decrease is predicted for low trap state density. When the trap state density is high, the major portion of the tunneling current is spin independent, resulting in a low MR. Thus low MR, large non-linearity and strong MR-V are correlated as observed. Further, a thicker barrier tends to result in a stronger MR-V dependence. These predictions have been confirmed by experimental results. It is concluded that trap states are mainly responsible for the observed MR-V dependency. To minimize this voltage dependence and to increase the MR. a high quality barrier with large barrier height and low trap density is essential. Thin barriers, which allow low device resistance for high speed and low noise applications. also help to decrease the MR-V dependence. These results suggest that the voltage dependence of SDT magnetoresistance can be used to study the trap state distribution in the barrier.

Magneto-Chromatic Effects of Tunable Magnetic Fluid Grating

Abstract: Recently, we have shown theoretically that a large enhancement in magneto-optical (MO) Faraday effect takes place in bi-gyrotropic magnetic films with disordered multilayer structures:'.' the films of interest are composed of Bi-substituted yttrium iron garnet (Bi:YIG) layers and SiO, layers which are piled up in a disordered sequence. The enlargement of the MO effect is strengthened remarkably by choosing appropriate film structures for supporting the localization of light within the films. In this paper, we show a huge MO effect arises when the film structure meets the socalled one-dimensional (magneto-)photonic crystal with a defect,' in which a Bi:YIG thin layer is sandwiched between two (Bi:YAG/SiO,) X k and (Si0JBi:YIG)x k reflection layers. For instance, the one-dimensional magneto-photonic crystal exhibits BF (Faraday rotation angle) 30 degl p m at h (wavelength of light) = 1.15 pm, the value of which is about 300 times larger than that of Bi:YIG single-layer film (BF=O.l deglpm). The unique MO effect of the one-dimensional magneto-photonic crystals was investigated in detail, for elucidating the huge enhancement of OF and for clarifying the design conditions of the media. It was found that the large 8~ of the medium originates from a slight difference in the localization conditions for two eigenmodes of lights in the Bi:YIG layers (tight-hand and left-hand circularly polarized lights). Then, provided that these eigenmodes of lights are strongly localized almost simultaneously, the onedimensional magneto-photonic crystal exhibits a considerably high MO effect with a high transmissivity. This situation can be realized when the structure of one-dimensional magneto-photonic crystal fulfills following conditions: n,d,=n,d,=h/4 and n , D M = m h / 2 with m=0.1,2;. . , where n, and n,? are, respectively, refraction constants of Bi:YIG and SiOz layers, while d , , d , , and DM are, respectively, thicknesses of Bi:YIG and SiO, reflection layers, and the center Bi:YIG layer.

Method and device for evaluating magnetoresistive effect head

Abstract: PROBLEM TO BE SOLVED: To make it possible to measure evaluating instability of the reproducing characteristic of a magnetoresistive effect magnetic head, by quantitating discontinuous change of magnetoresistive effect element resistance to a sense current while applying a static magnetic field from the outside to the intrasurface of the magnetoresistive effect element related to a head using the magnetoresistive effect element to a signal detection part. SOLUTION: Two pairs of horizontal direction magnetic field generating coils 7 and vertical direction magnetic field generating coils 8 are arranged so as to be orthogonally intersected in the intrasurface of the magneto resistive effect element 9. These coils are controlled by a horizontal direction magnetic field coil power source 10 and a vertical direction magnetic field coil power source 11, and can apply the magnetic field of optional direction and optional intensity for the magneto resistive effect element 9. Then, the sense current Ib is set optionally by a constant current source 12, and the resistance value R of the magneto resistive effect element 9 is calculated from the sense current Ib and a potential difference V. The quantitation of the discontinuous change of the electric resistance is performed by e.g. max [dR/dIb].

Voltage boosting type ignitor for motorcycle

Abstract: The utility model discloses a voltage boosting type ignitor for a motorcycle, which is composed of a magneto, an ignition circuit, a boosting circuit and a voltage regulating circuit. The boosting circuit is composed of the connection of a D1, a D2, a C1, an R1, a J, a T1 and a B1, wherein, the R1, the D2 and the T1 can form a voltage stabilizing circuit; low voltage generated by the magneto can be boosted to high voltage with from 200V to 400V through the B1. The voltage regulating circuit is composed of the connection of an SCR3, a D6, a D7, an R4, an R5, a C4, a C5 and a T2; alternating current generated by the magneto can applied to the anode of the SCR3 through a rectifier; under the functions of the R4, the D7 and the C4, a reference voltage is established on a control pole thereof; when the voltage of an accumulator is higher than the voltage, the control pole is in reverse-biased; the SCR3 can stop.

Test method for magneto-resistive magnetic head

Abstract: PROBLEM TO BE SOLVED: To provide a magnetic head test method capable of quantitatively evaluating Barkhousen noise being the noise of a magneto-resistive magnetic head SOLUTION: In this method, when the magneto-resistive effect type-magnetic head 2 provided with a magneto-resistive effect element changing resistivity by applying a magnetic field is tested, an AC magnetic field is generated by a magnetic field generation means 4 consisting of an oscillator 4a, a coil 4b, etc Then, the AC magnetic field from this magnetic field generation means 4 is detected by the magneto-resistive magnetic head 2, and the Barkhousen noise is tested

Spatial dispersion phenomena in magneto-optics

Abstract: An experimental study of nonreciprocal spatial-dispersion effects in para-(Cd1−xMnxTe), ferro-(LiFe5O8), and antiferromagnetic (Cr2O3) crystals caused by an external magnetic field or magnetic order is reported.

Magneto-resistive effect element and manufacture thereof

Abstract: PROBLEM TO BE SOLVED: To provide a magneto resistive effect element with a large resistance value which shows a large vertical current magneto resistive effect. SOLUTION: On a compound semiconductor substrate 1 composed of a (001) surface inclined in a [110] direction, a non-magnetic material and a ferromagnetic material are supplied alternately, thereby a magneto resistive effect film 4 comprising an artificial lattice structure of a non-magnetic material film 2 and a ferromagnetic material film 3 is epitaxial-grown almost vertically with respect to the compound semiconductor substrate 1. Thereby a magneto resistive effect element with a large resistance value showing a large vertical current magneto resistive effect is provided easily.

QUANTITATIVE DETERMINATION OF DOMAIN DYANMICS PARAMETERS IN Co/Pd MULTILAYERED MAGNETO-OPTIC RECORDING MEDIA

Abstract: Introduction Recently, magnetization reversal has been extensively studied in a number of magnetic films and interestingly, the contrasting behaviors of wall-motion dominant reversal and nucleation dominant one have been reported among similar samples of many systems(1,2]. These reversal behaviors have been analyzed by the thermally activated relaxation model based on Fatuzzo's theory[3,4] and also, compared with the theoretical predictions using micromagnetic simulations(5]. In this paper, we describe a new method to quantitatively analyze the magnetization reversal behaviors considering both the nucleation and wall-motion processes based on the time-dependent domain patterns. Model We modelize the time-dependent domain patterns of magnetization reversal based on circular domains formed by nucleation process and subsequently, expanded by wallmotion process as shown in FIG. 1. The expansion of the circular domain dr in time dt due to the wall-motion process is given by dr V dt, while the number of nucleation dn in time dt is given by dn = R ( s a )dt where V is the wall-motion speed, R is the dn =2 • •