Abstract: There are disclosed both one and two-dimensional, high resolution, brushless DC servomotors that are linear, rotary, planar and cylindrical in nature. All of these employ a capacitive method for deriving the required position and motor commutation information. In suitable circumstances, particularly two-dimensional planar motors on air bearings, the method allows the use of the motor ferromagnetic cores themselves as the capacitive position sensing elements. This leads to a particularly simple and compact type of sevomotor design. In addition, since such motors can move at high speed, there are also disclosed two transformer coupled methods for handling the current drive to the motor windings. Both methods are simple, energy efficient, applicable to motors of any number of phases, and in addition, handle motor direction reversals automatically.

Abstract: A magnetic circuit structure for use in an actuator, where the actuator has a displaceable assembly and a coil attached to such assembly, is shown to include flux conductors having generally parallel first and second poles defining gaps therebetween and an integrally formed base joining one end of the first and second poles so that the conductor defines a continuous flux path, and magnets attached to each of the first poles in the gaps so that flux from the magnets is directed across the gaps, wherein a portion of the coil passes through said gap, so that when a current is passed through the coil, the assembly moves.

Abstract: A reusable and regenerative electromagnetic propulsion method and operating system is provided for propelling high mass payloads to orbital velocities which does not require a vacuum environment. The propulsion system comprises a self supporting superconducting dipole coil several kilometers in diameter that is accelerated by magnetic repulsive forces generated by a plurality of giant superconducting field coils mounted in underground tunnels. The propulsion dipole is mounted inside a circular hypersonic wing-like structure equipped with movable aerodynamic control surfaces for guidance. The propulsion system can accelerate a payload with any desired launch azimuth by accelerating along a line of magnetic induction generated by the field coils having the desired azimuth angle. The payload is attached to the propulsion system by a plurality of cables.

Abstract: A linear reciprocating electromagnetic machine has an outer stator member having axially spaced apart pole pieces, an open-slot coil cavity housing a coil, and an inner stator member spaced from the outer stator member and providing means for completing a path for magnetic flux. The machine also includes a permanent magnet plunger arranged for reciprocation with respect to the stator members and within the space between such stator members. The plunger is provided with three permanent magnet segments arranged axially along the plunger such that the interface zones between the magnet segments are substantially within the region defined by the stator pole pieces for all operating axial positions of the plunger. The two outer magnet segments are of equal axial length while the center magnet segment is axially longer than an outer magnet segment by an amount equal to the axial length of the open slot of the coil cavity.

Abstract: A coil launcher having a barrel segmented into sections formed of sets of poly-phase energizable coils which are energized in succession by a power supply comprised of capacitors, with one capacitor coupled to a respective section of coils. A predetermined number of sections of coils disposed at the breech end of the barrel are merged, and the resultant merged section is coupled to a like number of pre-energized capacitors which are connected successively and cumulatively in series to that merged section of coils by way of switch circuits, whereby the number of capacitors connected in series increases over time to increase the level and resonant frequency of energy supplied to that merged section of coils.

Abstract: A supporting device including a first member which supports a springy means for resiliently supporting a second member. The supporting device includes a detection for detecting displacements of the springy with respect to the first member in accordance with the movement of the second member and a biasing which applies a force to the springy from the same direction as or from a direction opposite to that of the displacement for changing the elasticity of the springy in accordance with the movement of the second member.

Abstract: In a linear actuator comprising a motor-driven screw shaft, an overload detection mechanism comprises a pair of cup-shaped spring seats with substantially cylindrical portions. The spring seats are mounted at one end of the screw shaft by a pair of bearings and have a spring therebetween under a predetermined preload. Limit switches are provided for detecting overload on the screw shaft as a result of axial movement of the spring seats. The cylindrical portions of the cup-shaped spring seats serve as strikers for said limit switch means.

Abstract: Apparatus for repositioning garter springs around the pressure tubes of Candu-type nuclear reactors. A primary coil having a high permeability core is inserted into the pressure tube. The coil is energized by an alternating current of a frequency and amplitude sufficient to produce a primary alternating electromagnetic field that penetrates the wall and induces an eddy current in the garter spring. A secondary alternating electromagnetic field is also produced and is reactive with the primary field to produce a travelling electromagnetic field of sufficient intensity and of such direction that the resultant of the electromagnetic forces acting on the garter spring causes the spring to move along the tube.

Abstract: A flight motion simulator includes a unit under test supported on a stationary frame for angular and translational movement along pitch, roll, and yaw axes. A rotor element is secured to the unit under test and has a spherical configuration. Magnetic bearings supported by the stationary frame support the rotor element in three degrees of freedom of movement. A drag-cup induction motor is mounted on the frame and connected to the unit under test to generate three degrees of freedom of movement by generating a rotating magnetic flux in a stator assembly to induce a corresponding flow of currents in the rotor element to produce torque and motion in the unit under test in the same direction as the flux movement in the stator assembly.

Abstract: A voice coil-type linear motor comprising an cylindrical outer yoke made of a ferromagnetic material; a cylindrical center yoke made of a ferromagnetic material and magnetically coupled with the outer yoke; an integral, cylindrical magnet consisting essentially of an R-B-Fe alloy wherein R is at least one of rare earth metals such as Nd, Pr and Dy and having magnetic anisotropy in a radial direction, the cylindrical magnet being fixed to an inner surface of the outer yoke; a protective member made of a nonmagnetic and conductive material and fixed to a surface of the cylindrical magnet; and a movable coil means arranged in a magnetic gap between the center yoke and the cylindrical magnet.

Abstract: A dual flux path linear voice coil motor (VCM) for use as a disk file linear actuator has a magnetically permeable center core which is separated by non-magnetic insert into two sections spaced apart along a longitudinal axis parallel to the VCM's linear access direction. The center core has recessed parallel flat faces equally spaced on opposite sides of the longitudinal axis which form pockets in the center core. Permanent magnets are embedded in the pockets of the center core and span the space between the center core sections. The VCM generates is essentially constant force on the coil for a constant current, regardless of coil stroke position or direction of movement.

Abstract: A linear actuator comprises a pair of central poles symmetrically arranged parallel to the direction of motion of a carriage for transducers. Four permanent magnets are disposed around each central pole leaving predetermined gaps. Four ambient poles and one terminal pole surround the permanent magnets and each central pole. Two driving coils are slidably movable in the predetermined gaps therebetween. Upper and lower flat plate members support the driving coils so they may be fixed to the carriage. The central poles each have a rectangular cross-section, the permanent magnets surrounding the exterior four walls of the central poles leaving the predetermined gaps in which the driving coils are disposed. The ambient poles and terminal poles surround the central poles and form closed magnetic circuits. The flat plate members of the carriage are composed of ceramic material. The driving coils, arranged inside the predetermined gaps, are mounted at the ends of the flat plate members.

Abstract: A non-commutated linear motor particularly suitable for use as an electric door lock actuator for an automobile is disclosed. The linear motor may include a series of cup-shaped portions each having a winding appropriately connected to provide the desired travel stroke, in a direction determined by polarity of D.C. power applied to the winding, and power for the linear motor or a segmented armature designed to achieve the same flexibility in motor design and assembly.

Abstract: An electromagnetic projectile launcher is provided with muzzle circuitry which increases the rate of dissipation of inductively stored rail energy following the launch of a projectile and can be used to recover a portion of that stored energy for use in successive launches. The muzzle circuitry includes a pair of conductors which lie adjacent to the projectile launching rails and conduct current in a direction which is opposite to the current flow in the projectile rails. These conductors may be connected to a pulse transformer to increase the post-launch current of an inductive energy storage device. In an alternative embodiment, a capacitive muzzle circuit is used to store the inductive rail energy and inject current into the projectile launching rails during the launch of a successive projectile.

Abstract: A disk drive includes a linear actuator in which a single coil is mounted to the side of a carriage assembly and in association with a magnetic structure linearly moves the carriage assembly along upper and lower rails in positioning pickup heads on the surfaces of spinning disks. The carriage assembly includes a cantilevered roller support arm that is biased into engagement with the rails by a spring. The pick up heads are mounted on flexible arms attached to the carriage assembly, and the arms include cam members engage a non-magnetic stationary rod extending from the magnetic structure when the carriage assembly is moved to an extreme to travel thereby flexing the arms and lifting the heads from the surfaces of the disks.

Abstract: An alternator for repetitive pulsing of an electromagnetic projectile launcher is provided with a stator structure having at least one pair of single layer concentric coil portions which are electrically connected in parallel. A rotating magnetic field induces a voltage in these coil portions without producing circulating currents. The alternator is connected through a switch to a pair of genrally parallel conductive projectile launching rails and a sliding conductive armature between the rails. By causing the switch to conduct at a predetermined phase angle, the voltage across the launching rails can be reduced to zero as the projectile leaves the rails. Where a succession of projectiles is to be fired, the phase angle at which the switch begins to conduct is controlled in order to achieve a substantially constant muzzle velocity for each projectile while minimizing the rail voltage as each projectile exits the rails.

Abstract: The rotary actuator comprises sector-shaped magnets, with a coil located therebetween. A flexible printed cable is fixed on one surface of the coil, and opposes the magnets. The flexible printed cable extends inside the coil. The innermost end of a conductive wire constituting the coil is connected to the flexible printed cable inside the coil, without being guided between the coil and the magnets. Power is supplied to the coil through a cable located between the coil and the magnets. The coil generates a magnetic flux in response to the input current. A force acts on the coil by way of an interaction between the magnetic flux from the coil and the magnetic flux from the magnets. For this reason, the coil rotates about a rotating shaft of a head-support mechanism mounted on the coil. The head is then moved and positioned at a target track.

Abstract: A positioning table includes a pair of parallel rails defining an axis of motion. A movable assembly including a first linear motor assembly disposed for motion along one of the rails. An outboard linear motor assembly on the other rail is rigidly bridged to the first linear motor assembly for concerted motion therewith. The first linear motor assembly includes a plurality of permanent magnets defining a plane at a predetermined angle to the horizontal and an armature defining a plane at the same angle closely spaced from the permanent magnets. The permanent magnets may be disposed on the movable element of the linear motor assembly or on the first rail. The armature is disposed on the other of the movable element and the first rail. First and second bearings on the movable element of the linear motor assembly, which may be air bearings support loads in the vertical and horizontal directions.

Abstract: An electromagnetic actuator used with a segmented optical element includes a central pole piece that is affixed at one end to the segment, and is movable along a displacement axis. Oppositely wound, longitudinally displaced electical coils on the pole piece are encompassed by an outer magnet. Pole piece displacement is the result of the net axial force generated from the current flowing through the coils.

Abstract: A disk drive actuator including automatic eddy-current braking capability, enhanced by simple modifications of coil-mount structure, such as split damping ring DR and spaced-rib array, this array shown for example in FIG. 12 (see DR-R).

Abstract: A linear reciprocating machine has a tubular outer stator housing a coil, a plunger and an inner stator. The plunger has four axially spaced rings of radially magnetized permanent magnets which cooperate two at a time with the stator to complete first or second opposite magnetic paths. The four rings of magnets and the stators are arranged so that the stroke of the plunger is independent of the axial length of the coil.

Abstract: In a magnetic disc device, it is necessary that a magnetic head be positioned above an object data track at a high speed and with a high accuracy. This positioning operation is carried out by an actuator. In order to carry out a magnetic head-positioning operation at a high speed and with a high accuracy, it is necessary that a driving force generated by a magnetic circuit be applied to the center of gravity of the actuator. The techniques according to the present invention are characerized in that the center of gravity of the actuator and the position to which the driving force is applied are aligned with each other by regulating the distribution or position of the magnetic flux in the magnetic circuit.

Abstract: According to a preferred embodiment of the present invention, a double-ended moving coil linear actuator is provided comprising a cylindrical core and a hollow shell disposed around the core to define an annular space between the inner wall of the shell and the outer wall of the core. A non-magnetic spacer is mounted in the annular space to divide the annular space into first and second annular cavities, each of the cavities having a closed end adjacent the spacer and an open end. A first set of magnets is mounted within the first annular cavity to define a first magnetic circuit. A second set of magnets is mounted within the second annular cavity to define a second magnetic circuit. The magnets of these two magnetic circuits are sized and arranged to define a third "interleaved" magnetic circuit which is created by the interaction of the first two circuits. Each of the first two magnetic circuits has a dual-winding coil assembly associated with it.

Abstract: A linear actuator assembly for linearly the reciprocatingly moving magnetic heads in a magnetic disk storage apparatus. This linear actuator has a carriage for supporting magnetic heads, and a voice coil for moving the carriage. The sectional configurations of the carriage and the voice coil are equalized, thereby enabling the transmission of the driving force from the voice coil to the carriage without any eccentricity. This linear actuator also has a vibration absorbing mechanism for absorbing vibrations caused when the linear actuator operates, and a runaway prevention mechanism for limiting the movable range of the carriage.

Abstract: Disclosed is a single, integrated linear synchronous unipolar motor having high-energy permanent magnets operable along a substantially linear demagnetization curve and a polyphase coil. Collectively, the permanent magnets and polyphase coil provide for propulsion, suspension, braking and lateral control of a vehicle along a passive reaction rail. The permanent magnets provide the primary force for suspending the vehicle from the guideway, with a DC field control coil controlling the suspension gap between the vehicle and the reaction rail. The polyphase coil propels the vehicle along the track at a speed dependent upon the voltage and frequency of the supplied signal. The motor exhibits a high power factor and efficiency factor, resulting in a motor that can be operated from a power source having a lower KVA rating than that required for previous linear motor arrangements and that can be used in concert with a low-cost, passive guideway.

Abstract: A linear motor for magneto-optical disk drive or the like, including a movable member, a guide for guiding the movable member, a driving yoke provided at a central portion of the guide, an actuating member provided at the movabole member and a coil wound around the actuating member such that the actuating member is axially movably fitted around the guide. In the linear motor, a height of a line of action of a driving force produced by electromagnetic action between the coil and the driving yoke is so set as to coincide with a height of a centerline of the guide.

Abstract: An Earth-based, rapid-fire, electromagnetic accelerator system is provided for launching multiple hypervelocity nuclear or non-nuclear independently targetable warheads on ballistic trajectories to targets located anywhere on or above the Earth's surface. The warheads are mounted inside a reinforced launching sabot containing a plurality of coaxial superconducting dipole magnets. The sabot is magnetically accelerated to hypervelocities inside a large-bore vacuum tube by sequentially exciting a series of driving coils mounted coaxially along the tube. The sabots are injected into the tube from pre-evacuated storage canisters thereby eliminating the need for an air-lock. Terminal guidance systems allow the warheads to be fired over intercontinental distances to hit small, preselected targets with nearly perfect accuracy. The launch velocities are sufficiently high to enable warheads to also intercept and destroy orbiting satellites moving in space high above the Earth's surface.

Abstract: A supporting mechanism for a movable member of a linear pulse motor in which a magnetic flux is generated in a gap defined between opposing faces of a stator and a movable member so that the movable member is movable parallel to the opposing face of the stator along a linear passage. The supporting mechanism includes a pair of holding members disposed above the stator; a plurality of first rolling members, rotatably held in the holding members to be in rolling contact with the movable member and the stator and to form the gap, for movably supporting the movable member; a pair of guide members, opposingly disposed on the stator across the linear passage, for defining opposite sides of the linear passage; and a plurality of second rolling members, rotatably held in the holding member to be in rolling contact with the guide members and opposite lateral edges of the movable member.

Abstract: A power and free roller conveyor has a plurality of spaced rollers defining a conveyor path and to each of which is fixed a drive that comprises the secondary of a linear induction motor. The primary of the linear induction motor is positioned adjacent the drivers to enable an interaction of magnetic flux and current resulting from the propagation of a magnetic wave along the primary to cause the drivers and the rollers to rotate. The speed, torque, and direction of rotation of the rollers can be controlled by a voltage and frequency control unit.

Abstract: A linear motor-driven X-Y table includes a base and an intermediate saddle mounted on the base through linear bearings so as to be linearly reciprocatable in an X-axis direction. A table body is mounted on the intermediate saddle through linear bearings so as to be movable in a Y-axis direction perpendicular to the X-axis direction. A first linear motor is provided between the intermediate saddle and the base so as to be able to move the saddle linearly relative to the base, and a second linear motor is provided between the table body and the intermediate saddle so as to be able to move the table body linearly relative to the saddle.

Abstract: A linear motor-driven table apparatus is capable of operating both in fine-feed mode and large-feed mode. The table apparatus comprises a base, an intermediate carriage and a table body, the intermediate carriage and the table body being carried by the base through linear bearings such that the intermediate carriage and the table body are movable in the longitudinal direction of the base with respect to the base and with respect to each other. The movement of the intermediate carriage with respect to the base is effected by a first linear motor acting therebetween, while the movement of the table body with respect to the intermediate carriage is caused by a second linear motor acting therebetween. The amount of feed of the table body with respect to the base is controlled by controlling the supply of pulses to the first and second linear motors.

Abstract: Linear motor having a plurality of individually energizable coils along an axis. An armature member moves along the axis, and the coils are selectively energized to position the armature member along the axis. The motor is constructed in modular form and can be extended to any desired length by adding coil units and switching elements.

Abstract: A head access mechanism of the magnetic disk memory device for memorizing information by means of a rigid or flexible magnetic disk. The head access mechanism is equipped with a moving-coil type linear motor comprising an E-shaped yokes with two magnetic gaps and a movable coil. The yokes are arranged so as to produce the two magnetic gaps side by side on the extension itself of the plane of placement of the magnetic disk and/or plane parallel to it, with their openings opposing the magnetic disk. Magnets are installed on each of the magnetic gaps to align the magnetic flux toward the central yoke of the yokes. A movable coil is wound through the two magnetic gaps encircling repeatedly around the central yoke on which an indentation is provided, which extends parallel to the magnetic gaps.

Abstract: A linear motor of moving-coil type is disclosed, in which a multi-phase moving coil includes a plurality of flat coil units each not wider than the longitudinal length of a permanent magnet making up a stationary part divided by the number of coil phases, the flat coil units being arranged successively in the same plane with central parts not adjacently overlaid one on the other. The central parts of the moving flat coil units have a thickness equivalent to a single phase in spite of the multiple phases of the moving coil. Thus a great electromagnetic force is generated, and at the same time a high propulsive force is obtained with the magnetic flux density not reduced in the gap accomodating one phase of coils alone.

Abstract: A wide bandwidth linear motor system suitable for high performance applications such as driving the tuning plunger of a magnetron oscillator. The linear motor includes a coil assembly with a structure which suppresses secondary resonances, thereby permitting the linear motor to be used in a wide bandwidth servo control loop. The coil assembly includes a cylindrical coil support, a bushing coaxial with the coil support for attachment to the linear motor shaft, a plurality of radial ribs connecting the coil support to the bushing and a coil having multiple turns wound circumferentially around the coil support. The coil support is subdivided by axial gaps into at least two separate coil support elements, each connected by a radial rib to the bushing. Resonance of the coil support and the coil is suppressed by the separate coil support elements and the lossy connection therebetween.

Abstract: The device comprises two pick-up elements which can cooperate independently with a transmission line for control signals and are aligned in the direction of movement of a conveyor unit so as to be positioned respectively upstream and downstream in the direction of movement of the conveyor unit. The two pick-up elements are separated by a distance such that, during traversal of the gaps between successive sections of the line, at least one of the two pick-up elements is able to receive signals from the transmission line. A signal treatment circuit generates selectively an output control signal corresponding either to the single signal received by the two pick-up elements or to the control signal received by the pick-up element in the position upstream relative to the direction of movement of the conveyor unit when the pick-up elements receive different signals.

Abstract: A linear actuator has a flat box-like carriage movable along an access direction of a disk as a recording medium, a motor coil housed and fixed in the carriage, and a permanent magnet arrangement housed and fixed in the carriage to apply a magnetic field to the motor coil. The permanent magnet arrangement includes an E-shaped yoke member with a central portion extending along the access direction and inserted in the motor coil, a pair of outer portions arranged along two sides of the central portion, and permanent magnets arranged on opposite surfaces of the outer and central portions. The yoke member is arranged in the carriage to be parallel to the disk.

Abstract: A dual motor linear actuator is disclosed for use in a magnetic disc drive device. It includes a carriage reciprocatably guided between a pair of guide rails, with the accessing transducers being mounted to its inner end. Separate rectangular drive coils are affixed in symmetrical outboard relationship at the sides of the body of the carriage. The actuator assembly further includes two pairs of slab shaped magnets mounted to E-shaped magnet support structures that are integrally formed with the base of the disc drive device. The magnets are mounted to form two air gaps that are symmetrically disposed relative to a center plane and so that they respectively cooperate with the drive coils to apply motive forces on the carriage generally along two lines that are equidistantly spaced from the aforesaid plane of symmetry. The outer ends of pole pieces of the two magnet support structures are rigidly interconnected by a single plate that acts as an end pole piece for both magnet support structures.

Abstract: An improved carriage assembly for linearly reciprocating a data converter pickup or the like. Magnetic circuits are provided on each side of a carriage, and a driving coil wound on a transversely solid type coil bobbin which surrounds the carriage, is magnetically linked with the two magnetic circuits. Guide rails are provided between the carriage and the two magnetic circuits. The moving elements including the carriage, the driving coil, and the bobbin are supported on the guide rails for linear movement therealong by rollers.

Abstract: A linear DC motor adapted for driving a positioning table having a frame and a table displaceable in a linear direction has a toothed assembly affixed to one element thereof and an array of permanent magnets facing the toothed assembly mounted on the other element. Coils wound around the teeth of the toothed assembly and appropriately energized by DC produce a linear force which is effective to displace the table in a desired direction. When used with a position sensor and an appropriate control system, the table is controllable to a desired position. A set of brush members depending from the table contact a developed linear slip ring track for energizing the coils and for switching polarity of voltage to the coils at appropriate locations. In an embodiment where the coils are stationary on the frame and the magnets are disposed on the table, a power pickup arrangement movable with the brush members is incorporated into the brush and developed slip ring apparatus.

Abstract: A magnet controller for a magnetically suspended vehicle of the linear stator type for travelling along a rail track (1) forming a linear stator having teeth of uniform determined width, responds to a rectified control signal. The control parameters for the magnet controller (21) are adjusted in response to speed to assure a stable control during standstill and at low speeds and to achieve a good response or follower characteristic of the control system at high speeds. A speed representing signal (U.sub.v) is generated in a conductor loop, preferably a double loop (9), inserted into a groove (10) of the poles (5) of the levitation magnets (2). The signal (U.sub.v) generated in the conductor loop is rectified at (31), and if desired passed through a low-pass filter (32) to provide the control input signal for the controller (21) by a very simple circuit. Utilizing just the amplitude of the speed signal (U.sub.

Abstract: An apparatus is disclosed for actuating the read-write heads of a disk file in which a plurality of support rails having resilient bushings at either end support on their central portions a carriage for the read-write heads and on their resilient bushings the support structure for the magnets which drive the carriage during operation. Reaction forces arising in the magnets are thereby isolated from the support rails and the frame.

Abstract: This invention provides a structure for damping longitudinal vibrations in an apparatus which moves longitudinally.It employs, in a longitudinally moveable body, a structural element, slotted in the longitudinal direction, so that said structural element has relatively rigid upper and lower portions and relatively flexible flextures at the slot ends. A layer of elastomeric material covers a side of said element and a stiffening plate covers said elastomeric layer.

Abstract: A conveying apparatus of the type including a plurality of driving means disposed in the spaced relation along a track so as to allow a carriage to move on the track under the influence of inertia with the aid of propulsive force or reverse propulsive force which is generated by the plural driving means. The track has at least a curve and another driving means is disposed at the position upstream of the curve as seen in the direction of transportation of the carriage. To assure that the carriage moves along the curve at a proper moving speed a desired speed is so determined that centrifugal force exerted on the carriage is maintained at a level equal to or lower than a predetermined value. Speed controlling is effected in such a manner that the carriage is decelerated or accelerated from the moving speed detected at the time before it enters the curve to the desired speed by means of the last-mentioned driving means.

Abstract: A controlled electric drive (CED) device comprises a pair of rectangular magnetic poles of different polarity arranged adjacent, parallel, and congruent to each other with a relatively narrow gap therebetween, providing an essentially uniform magnetic field between the pole faces. The device further comprises a driver conductor arranged to move freely between the magnetic pole faces in such a manner that an electric current running through the driver conductor will tend to move the conductor out of the magnetic field at right angles to the conductor and to the direction of the magnetic lines of force defining the magnetic field. The device further comprises a controller conductor wound in a flat, essentially rectangular spiral fixed adjacent to, and insulated from, the driver conductor. The controller conductor is so arranged that its longitudinal direction is parallel to the driver conductor, and has first and second portions, with direct current flowing in opposite directions in each of the portions.

Abstract: An improved linear actuator for reciprocating a read/write head mechanism relative to magnetic disk storage system is disclosed, including a second, supplemental solenoid coil and associated magnet means in addition to the usual arrangement, and by way of improving linearity and efficiency.

Abstract: The invention relates to a method for controlling a closed loop linear position servo-motor having an armature including a first group of excitation windings and a second group of excitation windings, and a stator including field magnets disposed radially opposite the first winding group, and feedback windings disposed radially opposite the second winding group.

Abstract: A linear motor driving a carriage used in a magnetic memory. The motor includes a rotor portion having a hollow sleeve like member extending outwardly from the carriage at the side opposite to the magnetic head mounting portion of the carriage and a driving coil wound around the forward end of the hollow member; and a stator portion on the frame body of the magnetic memory and having a central yoke disposed within the hollow member along the direction of carriage movement, a U-shaped yoke surrounding the driving coil with the legs thereof being parallel to the central yoke, and a pair of permanent magnets mounted on the opposed faces of the legs of the U-shaped yoke. By means of this linear motor, the magnetic memory can be reduced in dimension.

Abstract: A linear disk actuator is disclosed incorporating a magnetic circuit for reducing stray magnetic fields in the region of the disks and recording heads of a magnetic recording disk system. The moving part of the actuator is provided with a plurality of coils mounted thereon, at least two of which are energized simultaneously and in magnetically opposing relationship to reduce the amplitude of the stray magnetic fields. Movement of the actuator is achieved by both energized coils interacting with a set of alternating poles positioned on the stationary part of the actuator.

Abstract: A first table is provided on a fixed base so that the first table can be moved in one of two directions which cross each other at right angles. A second table is provided on the first table so that the second table can be moved in the other direction. Linear motors for applying the driving force to the first and second tables to directly drive these tables are provided between the fixed base and first table and between the first and second tables.