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Showing papers on "Magnetic circuit published in 1980"


Book
01 Jan 1980
TL;DR: In this article, the dynamics of blood glucose and its regulating hormones are developed into a new model, building on the many previous attempts in this area, and the electrical and mechanical activity of the heart is modelled in the following chapter.
Abstract: whilst both the electrical and mechanical activity of the heart is modelled in the following chapter. The dynamics of blood glucose and its regulating hormones is developed into a new model, building on the many previous attempts in this area. As a contrast, the electrical rythms of the gastro-intestinal tract, which have received little attention to date, are dealt with in chapter six. The lungs, and mechanical properties of the respiratory system, have frequently been modelled, but in this section both mathematical and electronic descriptions are evolved which incorporate adaptive trackers, and results are presented from clinical applications of the techniques. Serious consideration is given to modelling circadian and related biological rhythms, with many of the proposed interconnected oscillator systems discussed, and finally a chapter is devoted to the concept of catastrophe theory applied to psychological modelling, with a detailed analysis of anorexia nervosa, the obsessive fasting by slimmers. Those interested in modelling biological systems will find this book very useful, since the references to each chapter are very thorough: however, the problems with the vast complexity of the human body, and the engineering problems of obtaining measurements, ensure that this is a field just opening up for research. PETER WATTS, Medical Engineering Unit, UMIST.

171 citations


Patent
06 Aug 1980
TL;DR: In this paper, an electromagnetic flow meter with less power consumption is presented, in which an instantaneous pulsate current with alternately changing polarity at given intervals is fed into an exciting coil, and a velocity of flow of fluid is calculated by using a voltage produced between electrodes in accordance with a residual magnetic flux of a magnetic circuit and a flow velocity of the fluid when no exciting current flows.
Abstract: An electromagnetic flow meter with less power consumption in which an instantaneous pulsate current with alternately changing polarity at given intervals is fed into an exciting coil, and a velocity of flow of fluid is calculated by using a voltage produced between electrodes in accordance with a residual magnetic flux of a magnetic circuit and a flow velocity of the fluid when no exciting current flows.

40 citations


Proceedings ArticleDOI
16 Jun 1980
TL;DR: In this paper, a new switching dc-to-dc converter is synthesized which consists of the least number of storage elements (inductive and capacitive) and switches, and yet truly emulates the ideally desired dc to dc transformer having both input and output currents as pure dc quantities with no ripple.
Abstract: A new switching dc-to-dc converter is synthesized which consists of the least number of storage elements (inductive and capacitive) and switches, and yet truly emulates the ideally desired dc-to-dc transformer having both input and output currents as pure dc quantities with no ripple. This result was facilitated by implementation of a new concept termed integrated magnetics, which leads in some special switching structures to the integration of otherwise independent and separate magnetic components (inductors and transformers) into a single magnetic circuit.

40 citations


ReportDOI
18 Nov 1980
TL;DR: In this article, the principle of magnetic pulse generation is briefly described and some of the basic guidelines used to design these circuits are discussed, and a demonstration of the principles by a small scale pulse amplifier is presented, and finally there is an extrapolation to a large scale system.
Abstract: The idea of using saturable reactors as the basis of high power pulse generators is not a new concept, but there have been few recent applications of this technology. Here the principle of magnetic pulse generation is briefly described and some of the basic guidelines used to design these circuits are discussed. A demonstration of the principles by a small scale pulse amplifier is presented, and finally there is an extrapolation to a large scale system.

38 citations


Patent
20 Mar 1980
TL;DR: In this paper, a fault indicator for indicating the occurrence of a fault current in an electrical conductor includes an externally viewable target which is positioned to a fault-indicating position by a trip circuit within the indicator.
Abstract: A fault indicator for indicating the occurrence of a fault current in an electrical conductor includes an externally viewable target which is positioned to a fault-indicating position by a trip circuit within the indicator upon occurrence of a fault current. The trip circuit is responsive to a magnetic field within a predetermined sensing plane generally parallel to the conductor. To increase the sensitivity of the indicator to the magnetic field of the conductor, the fault indicator includes flux concentrating pole pieces which form a low reluctance magnetic circuit between the circumference of the conductor and the sensing plane.

32 citations


Patent
24 Jan 1980
TL;DR: In this paper, an electromagnetic acoustic transducer is described, including a source of magnetic flux for establishing a static magnetic field, an electrical conductor for conducting an alternating current in the static magnetic fields, and an electrically conductive, nonmagnetic shield disposed between the source and the conductor.
Abstract: Disclosed is an electromagnetic acoustic transducer, including a source of magnetic flux for establishing a static magnetic field, an electrical conductor for conducting an alternating current in the static magnetic field, and an electrically conductive, nonmagnetic shield disposed between the source of magnetic flux and the conductor.

29 citations


Patent
26 Feb 1980
TL;DR: In this article, a magnetic pole structure of an isochronous cyclotron having a single helical winding for generating a complementary magnetic field to add to the main magnetic field is described.
Abstract: Disclosed is a magnetic pole structure of an isochronous-cyclotron having a single helical winding for generating a complementary magnetic field to add to the main magnetic field. The number of turns of the winding varies with radius, and a controlled electric current flows the single winding to build the complementary magnetic field as required.

27 citations


Patent
04 Jun 1980
TL;DR: In this paper, a lumped constant circulator and isolator are assembled in a fixed way to miniaturize and price low by assembling them in the fixed way, and a soft magnetic body is used as fixing metal fitting to make a magnetic circuit a closed circuit.
Abstract: PURPOSE:To miniaturize and price low a lumped constant circulator and isolator by assembling them in a fixed way. CONSTITUTION:On soft magnetic body 8, earth plate 10 is bonded hermetically and fixed and near the center over earth plate 10, shielding plate 11 in which two discoid ferrite cores 12 and three center conductors 13 have been contained is fixed hermetically. On cores 12, permanent magnet 9 is fixed in contact with shielding plate 11 and soft magnetic body 21 interposed. Further, magnet is covered with fixing metal fitting 22 from its upper part to fix magnet 9 to magnetic body 21. Thus, this can be miniaturized and priced low. Additionally, using a soft magnetic body as fixing metal fitting 22 makes a magnetic circuit a closed circuit, and consequently while permanent magnet 9 is miniaturized, the variation of characteristics due to an external magnetic influence can remarkably be reduced.

20 citations


Patent
21 Aug 1980
TL;DR: In this paper, a tachogenerator mounted on the underside of a brushless d.c. motor with an external permanent magnet rotor 11 and ironless stator coils affixed to a return magnetic path plate has a first winding surrounded by a first magnetic circuit for producing an alternating voltage of a frequency dependent upon speed of rotation and a second winding for compensation of the effect of the alternating stray flux penetrating through the tach generator.
Abstract: A tachogenerator mounted on the underside of a brushless d.c. motor having an external permanent magnet rotor 11 and ironless stator coils affixed to a return magnetic path plate has a first winding surrounded by a first magnetic circuit for producing an alternating voltage of a frequency dependent upon speed of rotation and a second winding for compensation of the effect of the alternating stray flux penetrating through the tachogenerator, the compensation being provided by superposing the output voltage of the second winding on the output voltage of the first winding. The second winding is arranged in a second magnetic circuit, such that upon revolution of the rotor, useful alternating flux is generated which is synchronous with that generated by the first magnetic circuit, but which is spatially in phase opposition thereto. A common rotor and a common source of magnetomotive force, such as a permanent magnet, are provided for both magnetic circuits, the magnet being an annular magnet with a large number of poles of alternating polarity, which cooperates with a toothed element of which the alternating recesses and projections are the same in number as the alternating poles of the magnet. The configuration is such that with relative movement, one part of the useful alternating magnetic flux generated flows around the winding of the first magnetic circuit in one sense, and another part of the same useful magnetic flux flows around the winding of the second magnetic circuit in the opposite sense. The ring magnet is preferably stationary and the toothed element is constituted by the outer portion of the rotor which revolves just inside the ring magnet. The second return path member carries at its center a bearing for the common shaft of the tachogenerator and the d.c. motor.

20 citations


Patent
Robert E. Canup1
23 May 1980
TL;DR: An ignition system that develops continuous-wave high-frequency spark signals is described in this paper, which employs a square wave oscillator which uses a unitary magnetic circuit and includes a control winding that acts to start and stop the oscillator.
Abstract: An ignition system that develops continuous-wave high-frequency spark signals. It employs a square wave oscillator which uses a unitary magnetic circuit and includes a control winding that acts to start and stop the oscillator. The control winding has a gate-turn-off type silicon controlled rectifier in circuit with it, which provides superior control action.

20 citations


Journal ArticleDOI
TL;DR: In this article, the performances of single layer and double layer motor were compared using the Fourier transform in the direction of motion of the magnetic circuit in two different ways, and the curvature of the secondary current lines were considered.
Abstract: This paper compares the performances of single layer and double layer motor. It establishes the expression of thrust in the form of an integral. An arbitrary extension of the magnetic circuit in the direction of motion is used in two different ways, which are compared. The finite width of the secondary, and the curvature of the secondary current lines are considered. Forces normal to the air gap are evaluated. The mathematical method is the use of the Fourier transform in such a way that the properties of every wavelength is considered.

Patent
Jean Delassus1
16 Jan 1980
TL;DR: In this article, an annular core with radially inwardly projecting teeth and a winding for generating a rotating magnetic field was presented. But the inductor was adapted for the electromagnetic rabbling of a billet in a continuous casting process.
Abstract: An electromagnetic inductor for generating a helically moving magnetic field includes a first magnetic circuit having an annular core with radially inwardly projecting teeth and a winding for generating a rotating magnetic field, and a second magnetic circuit formed by foliated bars and a second winding comprising an axial series of circular coils for generating an axially moving field. The two fields combine to generate a field with helical movement. At least some consecutive teeth of the core are hollowed to provide axial grooves in which the foliated bars are disposed. The coils of the second winding are cylindrical and set inside the cylindrical volume defined by the teeth. The inductor is particularly adapted for the electromagnetic rabbling of a billet in a continuous casting process.

Patent
17 Jul 1980
TL;DR: In this article, a flywheel for a manually-driven magneto megohmmeter with step variable voltage comprising a rotor formed by a ring of magnetic material carrying permanent magnets, and a stator, disposed inwardly of the rotor and formed by an assembly of magnetic circuits each having a C-shape with a coil wound around the central portion thereof and with two pole surfaces at the ends.
Abstract: A magnetic flywheel for a manually-driven magneto megohmmeter with step variable voltage comprising a rotor formed by a ring of magnetic material carrying permanent magnets, and a stator, disposed inwardly of the rotor and formed by an assembly of magnetic circuits each having a C-shape with a coil wound around the central portion thereof and with two pole surfaces at the ends. In order to reduce the starting torque, the number of pairs of permanent magnets is one less than the number of magnetic circuits, and the angular distance between the pole surfaces of one magnetic circuit is equal to the angular distance between two adjacent permanent magnets. Also, the arc length of each pole surface of a magnetic circuit is substantially equal to half the angular distance between two adjacent permanent magnets.

Journal ArticleDOI
01 Sep 1980
TL;DR: In this article, the results of an experimental and theoretical investigation of a disc-geometry homopolar synchronous machine with field excitation on the primary side were presented, and the results were validated by comparison with experimental data.
Abstract: The paper presents the results of an experimental and theoretical investigation of a disc-geometry homopolar synchronous machine with field excitation on the primary side. The unlaminated mild-steel rotor contained no windings and was brushless. The prototype machine produced approximately 75 kW of mechanical output at 3000 rev/min, with a product of power factor and efficiency greater than 0.7. The construction of the stator core was unusual and incorporated both laminated and unlaminated portions. The magnetic circuit was also arranged to minimise the axial force between the stator and rotor. A novel rotor design which achieved a reduced quadrature-axis reactance is shown experimentally to be superior to the conventional homopolar rotor. A three-dimensional magnetostatic computer program `GFUN? is shown to predict closely the flux densities prevailing in the machine. The quadrature-axis reactances calculated from these results also agreed well with measurements. An analytical method of calculating the axial force in the machine is validated by comparison with experimental data. The method uses the principle of Maxwell's stresses, and is based on the two-axis model of the machine. Prediction of the steady-state synchronous performance of the machine is also shown to be possible, using the two-axis model, provided that the assumptions implicit in that model are valid for the operating conditions of the machine. However, it was found that the output of the machine could be improved by a substantial amount by producing a degree of saturation in the magnetic circuit by means of the field winding. Under these conditions, the output of the machine exceeded predictions.

Patent
25 Jul 1980
TL;DR: In this paper, a switchable permanent magnet holding device is described, in which a permanent magnet rotatably disposed within a bore in a magnetic circuit block is rotated, so that the magnetism acting surfaces of the magnetic circuit blocks are brought into an exciting state for retaining a magnetic substance thereon and into a non-exciting state for releasing the magnetic substance from.
Abstract: A switchable permanent magnet holding device in which a permanent magnet rotatably disposed within a bore in a magnetic circuit block is rotated, so that the magnetism acting surfaces of the magnetic circuit block are brought into an exciting state for retaining a magnetic substance thereon and into a non-exciting state for releasing the magnetic substance therefrom. The permanent magnet is pressed against a stopper for impeding rotation thereof, due to a gyromagnetic force acting across the permanent magnet and the magnetic circuit block when the permanent magnet is rotated to a position in which the magnetism acting surfaces of the block become exciting.

Patent
15 Apr 1980
TL;DR: In this paper, an electromagnetic device which comprises an excitation coil wound to assume a substantially cylindrical shape having an axially extending hollow space is described. And a plunger made of a magnetic material accomodated within the hollow space for movement in an axial direction of the excitation coils between retracted and projected positions, and a permanent magnet made of intermetallic compounds of cobalt and one more rare earth elements disposed in the closed magnetic circuit so as to develop a magnetic force of attraction attracting the plunger onto the end of the yoke means opposed to
Abstract: An electromagnetic device which comprises an excitation coil wound to assume a substantially cylindrical shape having an axially extending hollow space; a plunger made of a magnetic material accomodated within the hollow space for movement in an axial direction of the excitation coil between retracted and projected positions; yoke means made of a magnetic material and engageable with one end of the plunger to provide a magnetic path which may be interrupted in response to the movement of the plunger towards the projected position, said yoke means extending between the respective ends of the excitation coil and positioned external of the said excitation coil to provide a closed magnetic circuit including the plunger and the magnetic path; a permanent magnet made of intermetallic compounds of cobalt and one more rare earth elements disposed in the closed magnetic circuit so as to develop a magnetic force of attraction attracting the plunger onto the end of the yoke means opposed to the end of the plunger and holding the plunger in the retracted position, said magnetic force of attraction being substantially cancelled by a magnetic force of the excitation coil when the excitation coil is energized; and means for covering the respective ends of the plunger and the yoke means so as to prevent powdered magnetic material from adhering to the respective ends of the plunger and the yoke means

Journal ArticleDOI
TL;DR: In this article, closed-form expressions for the integrals contained in the Fan equations for the magnetic field near a recording head are given for the Fan fields and conditions for approximating the more accurate Fan equations by the simple Karlquist equations.
Abstract: Closed-form expressions are given for the integrals contained in the Fan equations for the magnetic field near a recording head. The Fan fields are compared to the often-used Karlquist fields, and conditions are given for approximating the more accurate Fan equations by the simple Karlquist equations.

Patent
07 Apr 1980
TL;DR: A transducer for measuring a current, including a magnetic core which has a gap substantially impeding passage of any magnetic flux, a coil arranged to pass a premagnetizing current for producing a first magnetic field, a loop for carrying the current to be measured, and a magnetic field comparision device exposed to the magnetic fields as discussed by the authors.
Abstract: A transducer for measuring a current, includes a magnetic core which has a gap substantially impeding passage of any magnetic flux, a coil arranged to pass a premagnetizing current for producing a first magnetic field, a loop for carrying the current to be measured, so as to produce a second magnetic field, and a magnetic field comparision device exposed to the magnetic fields. The magnetic field comparison device includes a magnetic film bridging the flux gap. The film is alternately controllable in respective opposite directions of saturation substantially by the first magnetic field, and evaluates the measuring current in dependence of the magnetic fields. The magnetic core, the coil, the loop, and the magnetic film are substantially disposed concentrically.

Patent
04 Dec 1980
TL;DR: In this article, a device with a magnetic circuit for measurement of the d.c. in a primary winding using the compensation method and a secondary winding supplied with an a.c generator is presented.
Abstract: A device with a magnetic circuit for measurement of the d.c. in a primary winding using the compensation method and a secondary winding supplied with an a.c. operates with an accuracy unaffected by remanence and nonlinearities in the magnetic circuit magnetisation characteristic. A compensation d.c. is fed to a secondary winding so as to balance out the induction in the magnetic circuit due to the d.c. in the primary winding. The compensation current is used as a measure of the primary d.c. On input of an operational amplifier (12) is connected via an integrator (11, 14) to the secondary winding (3) a.c. generator (1) output. Its other output is earthed and its output drives a further secondary (20) with the compensation current.

Patent
10 Mar 1980
TL;DR: In this paper, a current sensing circuit monitors the currents flowing through the stator windings of a nutating motor, and when a predetermined winding current level is exceeded, the circuit produces an output signal which momentarily disables the current drive circuits for the windings, so that the wind currents are limited to levels sufficient to operate the nutating rotor.
Abstract: A current sensing circuit monitors the currents flowing through the stator windings of a nutating motor. The current drive circuits for the windings are capable of delivering large currents with a fast rise time so that the magnetic circuits of the nutating motor quickly saturate, providing precise operation of the motor. Steering diodes quickly discharge the windings into the power supply. When a predetermined winding current level is exceeded, the current sensing circuit produces an output signal which momentarily disables the current drive circuits for the windings so that the stator winding currents are limited to levels sufficient to precisely operate the nutating rotor. The sensing circuit has a hysteresis characteristic which in conjunction with the energy stored in a winding causes the current in a winding to be maintained between certain maximum and minimum levels.

Patent
03 Oct 1980
TL;DR: In this article, a high voltage power supply is used to transfer three-phase a.c. energy to d.c at full rated power over a large range of output voltages.
Abstract: A high voltage power supply used to transfer three-phase a.c. energy to d.c. at full rated power over a large range of output voltages. The electric and magnetic circuits are arranged according to the core type of construction wherein three legs of the iron core extend axially and have the primary coil wound along their full length. The core legs are joined for magnetic circuit continuity at the extremities. A plurality of high voltage decks each having three secondary winding modules mounted and interconnected are stacked axially over the axially extending iron core pieces. The secondary coils on each high voltage deck are interconnected in several three-phase connections, to produce a phase shift in the ripple of the d.c. output voltage of the various decks. A high voltage bridge rectification circuit mounted on each deck produces full wave rectification of the ouptut. Each high voltage deck provides a contact which is engaged selectively by contacts mounted on an axially extending rotary switch whose angular position varies the interconnections of the high voltage decks to produce a range of output voltages at the full rated power of the transformer. A counterbalance circuit to reduce any residual voltage ripple component at multiples of the input frequency includes the application of an a.c. voltage of proper phase and amplitude supplied at the ground return lead of the series-parallel connected high voltage decks. The counterbalance voltage is applied by way of an additional secondary winding of a few turns coiled over the three legs of the transformer core, but is completely independent of the primary and secondary windings. The number of turns of the additional winding and the leg from which the voltage is taken are determined empirically.

Patent
02 Sep 1980
TL;DR: In this article, the beads created along the edge during coating magnetic binder containing dispersions on a flexible support were removed by subjecting the coated dispersion to the stray field of a magnetic circuit consisting of permanent magnets and soft magnetic conductor elements, the central line of the gap of the magnetic circuit extending downstream the moving support at an angle up to 10° in the direction towards the border of the support.
Abstract: Elimination of beads created along the edge during coating magnetic binder containing dispersions on a flexible support by subjecting the coated dispersion to the stray field of a magnetic circuit consisting of permanent magnets and soft magnetic conductor elements, the central line of the gap of the magnetic circuit extending downstream the moving support at an angle up to 10° in the direction towards the border of the support.

Journal ArticleDOI
Yoshifuru Saito1
TL;DR: In this paper, the nonlinear magnetostatic fields in a saturable reactor were calculated by the method of magnetic circuits, and the magnetic circuits were used to measure the magnetic field.

Patent
16 Oct 1980
TL;DR: An electromagnetic induction pump comprises an open magnetic circuit with an excitation winding, where electric current is induced by the flow of an electrically conductive liquid, and the pump further comprises a means for electrical continuity outside the air gap of the magnetic circuit as mentioned in this paper.
Abstract: An electromagnetic induction pump comprises an open magnetic circuit with an excitation winding. Installed in the air gap of the magnetic circuit is a duct for the flow of an electrically conductive liquid wherein electric current is induced. The pump further comprises a means for electrical continuity outside the air gap of the magnetic circuit. This means for electrical continuity is in electrical contact with the conductive liquid being pumped and partially embraces the magnetic circuit. At least the magnetic circuit portions adjoining the duct have a length l, in the direction of the liquid flow, which is defined by the expression: ##EQU1## where σ=the specific conductivity of the conductive liquid being pumped; μ o =the magnetic permeability of the conductive liquid being pumped; and ω=the angular frequency of the alternating current source feeding the excitation winding, and provides a nearly exponential decrease of the magnetic induction in the duct along the length l, in the direction of the conductive liquid flow, to the value determined by the given length l.

Patent
14 Oct 1980
TL;DR: An adjustable flux generator used in conjunction with a Hall effect switch, comprising a coil and a magnetic circuit including an adjustable core, is described in this paper, where the coil produces a field of magnetic flux in response to the presence of an electrical current which is transmitted via the magnetic circuit to the hall effect switch.
Abstract: An adjustable flux generator used in conjunction with a Hall effect switch, comprising a coil and a magnetic circuit including an adjustable core. The coil produces a field of magnetic flux in response to the presence of an electrical current which is transmitted via the magnetic circuit to the Hall effect switch. The adjustable core is disposed to be manually adjusted to control the amount of magnetic flux delivered to the Hall effect switch. When the flux exceeds the Hall switch operate point the switch produces an output signal.

Patent
22 May 1980
TL;DR: In this article, the authors proposed to realize a miniature and lightweight device and also to eliminate nearly leakage of magnetic flux by arranging four flat fan-shaped magnets on opposite surfaces of a couple of flat yokes.
Abstract: PURPOSE:To realize a miniature and lightweight device and also to eliminate nearly leakage of magnetic flux by arranging four flat fan-shaped magnets on opposite surfaces of a couple of flat yokes. CONSTITUTION:In inside surfaces of a couple of upper and lower support boards 23 and 24 combined in one by support 22, shallow grooves 27 at centers of mutually-opposing surfaces nearly in a fan shape and constituting a magnetic circuit part are formed and flat yokes 25 and 26 with four flat magnets 28a-29b nearly in a fan shape and fitted at both ends are arranged opposing each other. Further, flat moving coil 20 of narrow coil width fixed to axis 2 through coil frame 21 is inserted among magnets 28a-29b so that winding parts 20a and 20b crossing its sliding direction will be positioned at magnet gap parts 30a and 30b. Consequently, flowing a current through coil 20 forms a magnetic circuit of yokes 25 and 26 at the shortest distance, so that yokes 25 and 26 can be miniaturized and the leakage of magnetic flux can also be reduced.

Patent
06 May 1980
TL;DR: In this article, a nonmagnetic insulator layer comprised of ceramics of ZnO-Bi2O3-CuO system is inserted between the laminations of magnetic bodies.
Abstract: PURPOSE:To obtain the laminated coil of the open magnetic circuit type and contrive the wide range improvement of a superposition characteristic and a temperature characteristic by a method wherein a nonmagnetic insulator layer comprised of ceramics of ZnO-Bi2O3-CuO system is inserted between the laminations of magnetic bodies. CONSTITUTION:Magnetic ferrite powders knealed with a suitable binder to be made paste are printed in sheetlike to form a magnetic body layer 1, and a conductive paste of Pd-Ag and the line is printed setting aside the upper part of the layer 1 to form a conductor 2. A conductor pattern extending spirally between the magnetic body layers is formed in the same manner. Then, the nonmagnetic insulator layer 7 is printed using the paste containing the ceramic powders of the ZnO-Bi2O3- CuO system, and one end of the conductor 6 is exposed and the magnetic body layer 9 is printed again. Thus, magnetic fluxes are not leaked outside the laminated bodies due to the magnetic body layers 1, 11, a part corresponding to a gap being formed due to the presence of the insulator layer 7, the laminated coil of the open magnetic circuit type being obtained, and the temperature characteristic or the like can largely be improved.

Patent
23 Apr 1980
TL;DR: In this paper, a ring shape perforated substance 15 of nonmagnetic substance is contained in the gap in the magnetic circuit so that the substance 15 is not allowed to contact with a voice coil 10, and a cooling liquid 12 with good heat transfer such as high class alcohol, glycerol and water and without compatibility for a magnetic liquid 11, is put in.
Abstract: PURPOSE:To prevent cooling liquid from being jumped out due to shock, by sealing nonmagnetic perforated substance including cooling liquid and magnetic liquid sealing the cooling liquid, in a ring shape magnetic air gap, and cooling a voice coil in the magnetic air gap. CONSTITUTION:Ring shape grooves 6, 6' are provided at a part in which a center pole 2 and a yoke 5 are opposed out of a yokes 1, 5, center pole 2 and a magnet 4 forming a ring shape magnetic air gap. Further, a magnetic liquid 11 scattering magnetic ultra fine particles in coroid in nonvolatile solvent is filled in the grooves 6, 6' to prevent the leakage of the cooling liquid. A ring shape perforated substance 15 of nonmagnetic substance is contained in the gap in the magnetic circuit so that the substance 15 is not allowed to contact with a voice coil 10, and in the magnetic gap, a cooling liquid 12 with good heat transfer such as high class alcohol, glycerol and water and without compatibility for a magnetic liquid 11, is put in. The perforated substance 15 is formed with metal baking nonmagnetic substance powder such as copper, blowing metal, or ceramic material such as aluminum oxide.

Patent
28 Mar 1980
TL;DR: In this paper, the optical pickup main body 2 is lighter than the weight of the magnetic circuit 13 and connected to the circuit via the support 5 rigid toward x and y and soft toward z.
Abstract: PURPOSE:To enable the device with high reliability, by making the pickup main body toward three coordinate axes movable independently. CONSTITUTION:When the permanent magnet 7 is magnetized, magnetic lines go toward the arrow C at the part located with the voice coil 4, and the magnetic lines go toward the arrow B at the part located with the coil 12. Thus, when electric current flows to the voice coil 4, the force toward z is caused between the optical pickup main body 2 and the magnetic circuit 13. The optical pickup main body 2 is lighter than the weight of the magnetic circuit 13 and connected to the magnetic circuit 13 via the support 5 rigid toward x and y and soft toward z. Further, the circuit 13 is connected to the frame 11 via the support 10 soft toward x and y rigid toward z. Thus, most of force toward z caused between the optical pickup main body 2 and the magnetic circuit 13 is used to displace the optical pickup main body 2 toward z and the magnetic circuit 13 is not almost moved.

Patent
06 Aug 1980
TL;DR: In this article, the power consumption of the flow meter is decreased by applying to exciting coils (5a,5b) a pulsating alternating current (1) with short time duration.
Abstract: The power consumption of the flow meter is decreased by applying to exciting coils (5a,5b) a pulsating alternating current (1) with short time duration. The velocity of flow of fluid in pipe (1) is determined using the voltage produced between electrodes (2a,2b) during a predetermined constant period. This is from the point when the flux in the magnetic circuit reaches a stable level and no exciting current flows in coils. The magnetic circuit may be comprised of a series coupling of a yoke made of high permeability with low residual magnetic flux and a permanent magnet.