Abstract: A device for providing a low-cost mounting arrangement for a hall effect device to sense the speed of an electric motor. The device uses a plastic base fixed to or integrated into the motor bearing support and designed to hold a standard mass termination connector, hall effect device and leadwire harness which passes digital information to a circuit board for motor speed control.

Abstract: The present invention relates to an apparatus having spaced permanent magnets positioned so that there is magnetic interaction between them, and controlling the interaction by having a coil in the space between the permanent magnets connected to a source of electric potential and a controllable switch in series such that closing the switch places a voltage across the coil and predeterminately affects the magnetic interaction between the spaced permanent magnets. The invention also teaches mounting one of the permanent magnets on a rotatable structure so that the spaced permanent magnets can move relative to each other, the controllable switch operating to control the application of electric potential across the coil in such a manner as to produce relative rotational movement between the spaced permanent magnets.

Abstract: A grinding machine provided with a spindle rotating under the influence of a cantilever mounted rare earth permanent magnet motor. Hydrostatic fluid film bearings are provided between the ends of the spindle and a bronze bearing to support the spindle in such a manner so as to eliminate wear. A single oil reservoir is used to supply oil to the hydrostatic bearings, as well as to the cooling jacket of the motor.

Abstract: The brushless DC motor comprises at least one multi-pole composite magnet which functions as a rotor, at least one stator member which determines the angular position of this rotor, means for positioning the rotor(s) and the stator member(s) on a common axis, a sensing device for determining the position of the composite magnet relative to the stator member(s), and means for determining the magnetic configuration on the stator member. The composite magnet comprises two sections, each section having a plurality of projections and apertures. The projections and apertures on a first section mate with the apertures and projections, respectively, on the second section. The first and second sections are magnetized in opposite axial directions. In one embodiment, each stator member has a plurality of pole pieces which are positioned in operative relation to the composite magnet. Two windings are formed on each stator member.

Abstract: A motive power generating device comprises a permanent magnet disposed around a rotational output shaft for rotation therewith, the output shaft being mounted on a support member for rotation, a magnetic body disposed in concentric relationship with the permanent magnet for rotation with the rotational output shaft, the magnetic body being subjected to magnetic flux generated by the permanent magnet, a plurality of electromagnets fixedly mounted to the support member in such a manner that they are spaced at predetermined distances around the periphery of the magnetic body, each magnetic circuit of the electromagnets being adapted to be independent of one another, and excitation change-over means for the electromagnets, the excitation change-over means being adapted to sequentially magnetize one of the electromagnets which is positioned forwardly with regard to a rotational direction of the rotational output shaft, so as to impart to the particular electromagnet a magnetic polarity opposite to that of the magn

Abstract: A rotation detecting apparatus including a magnet having alternatively-arranged N-poles and S-poles on a rotator, and a magnetoresistive element having plural (six) magnetoresistive units which are continuously arranged at a predetermined interval on a stator, and signal output units which are provided at prescribed three positions of connection points of the plural detection units, wherein the detection units serving to detect magnetic field which is varied in accordance with rotation of the rotor, and the signal output units serving to output signals whose phases are different from one another by 120.degree. on the basis of the detection of the magnetic field by the detection units.

Abstract: A three-phase brushless dc motor includes a permanent-magnet rotor magnet arrangement having at least four poles and a Y-connected, or star-connected, three-phase stator winding. The winding's phases are arranged non-overlapping in slots of a slotted stator, the currents flowing in the three phases being controlled via at least three semiconductor elements by at least three magnetic-field-sensitive rotor position sensors. Each sensor is associated with a respective two of the winding's three phases and triggers a commutation which switches off the current in one of the associated two phases and switches on the current in the other of the associated two phases. The sensors are located to sense the permanent-magnet flux emanating from the rotor poles themselves. The rotor position sensors are provided at special angular locations on the stator.

Abstract: An electric motor used for example in a magnetic disk drive, comprises a rotor having a hub on which the magnetic disk is mounted, and an annular driving permanent magnet, and rotating together with a rotary shaft, and a stator disposed outside the rotor, having a core and coils wound on the core. A signaling permanent magnet for detecting the rotary angle or the rotational speed of the rotor may be provided on the radially inner side of the driving permanent magnet. Part of the outer periphery of the stator core may be retracted radially inward or cut away to form a concavity or an open part. A magnetic shielding plate may further be provided to cover the coils, with part or the entirety of the magnetic shielding plate being positioned closer to the rotary shaft than the outermost periphery of the rotor to prevent the escape of the rotor in the direction of the rotary shaft.

Abstract: An electric rotary machine which prevents problems involved in leakage flux, and reduces the number of components so that it becomes thin and small in size, and inexpensive. The machine includes a first pulse generating device generating a first frequency generating signal consisting of P1 uniformly spaced pulses per one revolution of the rotor by detecting a counterelectromotive voltage induced in a rotary magnetic field generating device while a driving magnet is rotating, a magnetic body producing magnetic flux during rotation of the rotor, a second pulse generating device generating a second frequency generating signal consisting of P2 uniformly spaced pulses per one revolution of the rotor by detecting changes in the magnetic flux of the magnetic body, and an index position detecting circuit generating an index signal on the basis of a periodic phase difference between the first and second frequency generating signals.

Abstract: An apparatus for sensing the relative rotational position between first and second relatively rotatable members includes a transmitter disk having a planar surface and being mountable to the first member so that the planar surface of the transmitter disk is substantially perpendicular the an axis of rotation of the first and second members. The transmitter disk has a conductive material mounted to the planar surface in a circular pattern with a sinusoidal diameter. A receiving disk having a planar surface and is mountable to the second member so that the planar surface of the transmitter disk is substantially perpendicular the an axis of rotation of the first and second members. The receiving disk has a conductive material mounted thereon and arranged in a circular pattern with a squarewave diameter so as to receive a signal from the transmitter disk and output a signal indicative of the relative rotational position of the first and second members.

Abstract: A homopolar reluctant sensor comprises a magnetic material rotor including a cylindrical body having at a first end a laminated part comprising the same number of lobes as there are sensor pole pairs and at a second end a ring and a magnetic material stator comprising a cylindrical portion provided with an excitation coil energized by an alternating supply, a first ring having notches and defining with said laminated part a first airgap and a smooth second ring defining with said rotor ring a second airgap. The stator notches are provided with a winding such that the voltage induced therein is sinusoidal and free of harmonics. The envelope of this voltage represents, apart from a phase-shift, the position of the rotor relative to the stator.

Abstract: An electromechanical transducer having a first element movable in relation to a second element, wherein the first and second elements perform a translational movement relative to one another. A transducer element mechanically coupled to the first element and second elements for converting the translational movement into an electrical signal. A transmission element converting the relative translational movement of the first and second elements into a rotating movement of the transducer element so as to produce the electrical signal.Applicant claims, under 35 U.S.C. .sctn.120, the benefit of priority of the filing date of Jun. 17, 1991, of International Patent Application PCT/NL91/00099, copy attached, filed on the aforementioned date, the entire contents of which are incorporated herein by reference. Applicant also claims, under 35 U.S.C. .sctn.119, the benefit of priority of the filing date of Jun. 19, 1990, of Netherlands Patent Application No.

Abstract: A brushless DC drive motor with an external rotor has three pole shoes on a substantially ring-shaped stator for each two poles on the rotor. The stator winding is commutated by a three-phase commutation network in such a fashion that first, second and third networks in the stator winding are cyclically connected to an external DC source in accordance with rotor position. Each of the networks comprises at least one stator coil wrapped around a neck of a single corresponding one of the pole shoes.

Abstract: A plurality of stepper motors, each of which comprises a stator assembly and a rotor, are axially aligned to form with a control system an encoder for use in a printing apparatus. The rotors constitute print wheels which support different print characters. The stator assembly of each motor only extends above a part of the circumference of the associated rotor. This enables the axial extent of the print wheels to be reduced, A sensor arrangement is provided to enable the home position of each wheel to be determined. In operation, the control system receives desired print character information and rotates the associated rotor to the correct position for printing to take place. Once all rotors have been rotated to their desired position for printing, printing can then take place. The arrangement enables the printing process to run faster than previously.

Abstract: A position detection apparatus for a switched reluctance motor wherein a single sensor is used for detecting a rotor position and thus driving the motor. A sensing unit is provided with a single sensor for detecting a position of a rotor, a start signal generation circuit, for generating a start signal for aligning the rotor with a stator upon starting, a position detection signal input circuit for passing the position detection signal following the start signal, a drive control pulse generation circuit, for receiving an output signal from the position detection signal input circuit as a clock signal, sequentially shifting driving signals for respective phases and generating drive control pulses for respective phases, and a phase excitation circuit for logically combining phase drive control pulses from the drive control pulse generator with the start signal from the start, signal generation circuit and exciting the phases sequentially.

Abstract: An electromagnetic motor of the finite rotational type has an improved rotor-returning mechanism for exerting a magnetic force to return its rotor to the initial angular position in a non-excited condition. The rotor-returning mechanism is comprised of a permanent magnet fixedly mounted on a stator and a permanent magnet mounted around the rotor. The permanent magnets are arranged such that, a magnetic attractive force generated between the permanent magnets functions to return the rotor to the initial angular position. The rotor-returning mechanism can be constitued by first and second ring-shaped permanent magnets mounted on the rotor. The N and S poles of the first magnet are offset in a the circumferential direction from those of the second magnet so as to generate a magnetic torque for returning the rotor to the initial angular position.

Abstract: An electric motor consisting of an inside stator part and a rotor part placed outside and concentrically in relation to the stator part, has a high number of permanent magnets (13) on the inside of the rotor part. The magnetic fields from these permanent magnets interact with magnetic fields between flux-conducting lamella blocks (30, 35) engaging the coil cores (8) on the stator. The lamella blocks (30, 35) are T- and .GAMMA.-shaped with top beams (25, 27) pointing in directions parallel to the axis, and the top beams (25, 27) are positioned to provide substantially circumferentially directed magnetic fields in flux gaps (36) therebetween. The magnetic fields in the flux gaps (36) between the top beams (25, 27) are reversed in successive order, and under time control from an electronic regulator.

Abstract: A vehicle lighting system having a central light producing unit and bundles of optical fibers for the transport of light to lighting fixtures is provided. The central light-producing unit has a defined axis and at least one light source for producing light. The central light producing unit includes means for rotating the at least one light source about the axis. The light system further includes at least one light guide for receiving and guiding light produced by the at least one light source to at least one lighting fixture. The at least one light source is preferably rotated about a support collar which has at least one light guide, but preferably a plurality, connected to the collar. The light guides are preferably equally spaced about the periphery of the collar and which light guides receive and transport the light to light fixtures appropriately arranged in or on the vehicle.

Abstract: The present invention relates to a compact guide unit and direct drive unit wherein, since plugs are arranged to cover the openings of insertion holes formed for insertion of fastening members in a track rail for one of either a detected element or detecting element that compose a position detection device for detecting the relative position of said track rail and a slider, the amount of space occupied by said position detection device can be made to be extremely small thereby allowing overall size of the unit to be reduced.

Abstract: A direct current linear motor and direct drive unit that has a thin shape, is inexpensive and effectively dissipates heat from heat-generating electronic components.The above-mentioned advantages are obtained as a result of using a coil yoke as a circuit board by attaching electronic components and so on to said coil yoke equipped on a primary side.

Abstract: A rotating machine having a rotor comprising a flexible shaft with a plurality of masses distributed along the shaft. Included within these masses are magnetic disks. Magnetic bearings are attached to the housing and coact to support the rotor in only a radial direction or in both radial and axial directions. Bearing sensors are used to measure the shaft position local to each bearing relative to a face of each bearing. Variable magnetic bearing parameters are controlled so as to change values of stiffness and damping of the magnetic bearings in response to the measurements from the bearing sensors. These controls can be direct analog circuitry, or digital components, or a combination of digital and analog components.

Abstract: A radial magnetic bearing apparatus suspends a rotating shaft and stably operates at a level exceeding a bending intrinsic vibration value of the rotating shaft by controlling magnetic forces generated by control coils wound around control magnetic poles. Grooves are provided on the surface of each control magnetic pole facing the rotating shaft, and sensor coils are wound to pass through the grooves in order to detect the position of the rotating shaft in the radial direction. A part of each control magnetic pole may be used as magnetic poles of an inductance-type displacement sensor.

Abstract: A permanent magnet generator includes a rotor having poles wherein one of poles of the rotor is non-magnetic. A stator has stator windings wound in cooperation with the poles of the rotor. The non-magnetic pole establishes at least one predetermined position of the rotor. A sensing coil is wound on the stator. The sensing coil responds to the non-magnetic pole by providing an electrical signal indicative of the predetermined position of the rotor.

Abstract: A magnetic bearing system includes a rotor with a plurality of masses distributed along the shaft including a portion having a circular peripheral surface suspended radially from pole pieces of permanent and electromagnets. A fault tolerant adaptive system responds to detected parameters of the rotor for varying the stiffness and damping the rotor. Position and speed of rotor are sampled at a rapid rate for each of a plurality of control axes and are processed independently during each sampling period. Malfunction of any of the processors causes supervisory controller to reconfigure the processing of the samples.

Abstract: A reluctance type motor capable of rotating at a high speed with a large output torque has transistors (20a-20f) connected to both ends of phase exciting coils (39a-39c), a current supply control circuit for successively activating the exciting coils in response to position detecting signals, which represent rotor rotational positions to be detected by position detecting elements, and diodes (21a-21f) connecting the exciting coils and capacitors (47a-47c). When a current supply to the exciting coil is stopped, the capacitor is promptly charged by a magnetic energy stored in the exciting coil to extinguish the magnetic energy and also to rapidly build up an exciting current supplied to a subsequently activated exciting coil by use of a charged voltage in the capacitor.

Abstract: A permanent magnet brushless torque actuator is comprised of an electromagnetic core capable of generating an elongated toroidally shaped magnet flux field when energized. Outside the generally cylindrical coil is an outer housing with upper and lower end plates at each end. Mounted to the end plates and extending towards each other are stator pole pieces separated from its opposing pole piece by an air gap. A permanent magnet rotor is disposed in the air gap and mounted on a shaft which in turn is rotatably mounted in each of the end plates. The permanent magnet rotor comprises at least two permanent magnets, each covering an arcuate portion of the rotor and having opposite polarities. Energization of the coil with current in one direction magnetizes the pole pieces such that each of the two pole pieces attracts one of the magnets of the rotor and repels the other magnet of the rotor resulting in a torque generated by the output shaft.

Abstract: A polyphase brushless DC motor has an integral automatic feedback arrangement affording excellent accuracy and a high degree of magnetic balance. The stator pole elements of the motor are identical and equidistantly spaced, and each is wound with two coils. One coil on each pole element comprises sensor circuitry; the other comprises power circuitry. As a result, all pole elements of the stator are utilized both to produce rotor drive torque and also to generate electrical signals that provide highly accurate rotor-position information.

Abstract: A brushless electric motor with Hall-effect sensors is configured to provide its stator structure with a portion which projects axially away from a main armature. The projecting portion is radially congruent with a second, smaller armature coaxial with the main armature, with a portion of a sleeve in which the sensors are disposed in circumferentially spaced configuration, and with a laminated annular shield iron. The annular shield iron is radially interposed between the projecting portion of the stator structure and the sensors. In this configuration, the shield iron serves to close the magnetic field originating from the second armature and interacting with the sensors while simultaneously shielding the sensors from field effects attributable to current flow in the axially projecting portion of the stator structure.

Abstract: A magneto dynamic machine, which may be an electric motor not having a commutator, for example one having electronic commutation, has a permanent magnet rotor comprising a rotor shaft carrying a rotor body, the rotor being provided with permanent magnet elements. The latter consist of a plurality of segments of magnetic material, retained in position by clamping rings engaging around free ends of the magnetic segments. The space between each segment and the next is occupied by a spacing bar.

Abstract: A two-pole toothless PM machine employs Hall effect sensors to indicate the position of the machine's rotor relative to power windings in the machine's stator. The Hall effect sensors are located in the main magnetic air gap underneath the power windings. The main magnetic air gap is defined by an outer magnetic surface of the rotor and an inner surface of the stator's flux collector ring.

Abstract: A DC motor pulse signal generating device comprising a DC motor including a rotor frame with a magnet for pulse generation and a substrate for supporting the rotor frame. A magnetic sensor is mounted on the substrate for detecting magnetic flux generated from the magnet and outputting a signal. A positioning groove is formed on the substrate to receive the magnetic sensor on a fixed position. Thereby, the gap between the magnetic sensor and the magnet is fixed so that stable pulses are generated, and the height of the center of the magnetic sensor is lowered to the level of the center of the magnet so that magnetic flux is detected most efficiently by the magnetic sensor.

Abstract: A method and apparatus for the accurate non-contact detection and measurement of static electric charge on an object using a reciprocating sensing probe that moves relative to the object. A monitor measures the signal generated as a result of this cyclical movement so as to detect the electrostatic charge on the object.

Abstract: A stepping motor having a printed circuit rotor including a first printed circuit on one side of the rotor formed in a plurality of spiral coil windings, and a second printed circuit on the other side of the rotor formed in an equal number of like coil windings, the coil windings on one side being 90.degree. out of phase with those on the opposite side. The motor also includes a slip-ring arrangement for delivering pulsed DC power alternately to the first and second printed circuits for driving the rotor in a step-wise manner.

Abstract: A sensor for measuring the angular position of a rotor relative to a stator has firstly a rotor made of a magnetic material and including 2 p lobes, where p is an integer. A stator is positioned around the rotor. The stator is made of a magnetic material and includes a number of teeth equal to 2n.p, where n is the number of phases of the sensor. Each tooth is surrounded both by an excitation first winding and by reception second winding. The excitation windings are connected together in series and disposed on the teeth such that the windings on two circumferentially adjacent teeth produce magnetic flux in opposite directions. The set of said excitation windings are powered by an alternative current or voltage. The reception windings of the same phase and offset by 180 electrical degrees are connected together in series. The envelope of the signal at the terminals of each of the pairs of reception windings represent the angle of rotation of the rotor relative to the stator, to within a scaling factor.

Abstract: A revolutions per minute (RPM) control device for hand-held electric tools, such as drilling tools and hammer drills, has a RPM sensor in a separate housing or container from the control device housing. The sensor is connected to the control device by a flexible cable. The sensor extends through an opening in the drive motor housing of the electric tool. The RPM control device can be used for a plurality of similar types of tools.

Abstract: A hybrid single-phase variable reluctance motor (31) has a stator (33) having a plurality of inwardly salient teeth (41A-41D) terminating at a central bore (37). The teeth are arranged in generally diametrically opposed pairs of teeth and are generally evenly spaced around the bore. A phase winding (43) is operatively associated with one pair of the stator teeth. The winding, when energized, causes a temporary magnetization of the stator teeth. A rotor (35) is disposed for rotation in the bore and has outwardly salient teeth (45A, 45B) generally diametrically opposed to each other. A permanent magnet (53) is disposed adjacent the bore at the end of one tooth (41D) of a second pair (41C, 41D) of stator teeth. One tooth (41D) of the second pair of stator teeth is offset with respect to a longitudinal axis (A.sub.1) of the second pair of teeth. This offset acts to eliminate a stable detent position in which the rotor could otherwise "park" itself when it stops running.

Abstract: A tachometer for monitoring the rotation of an output shaft (e.g. of a motor, where the motor is enclosed within a standard NEMA housing), includes an enclosure (e.g. adapted to be secured to an end plate of the motor housing), the enclosure having a radial center and a longitudinal axis which, when the enclosure is secured to the housing, are aligned with a longitudinal axis of the output shaft. The enclosure has at least one mounting surface in a peripheral wall portion thereof, the mounting surface having an aperture formed therein which opens in a radial direction. A sensor module including a pair of axially aligned magneto-resistive sensors is mountable on the mounting surface of the enclosure such that the module protrudes through the aperture with the sensors facing radially inwardly.

Abstract: A DC commutatorless motor in which one pulse is generated per one revolution is disclosed. The motor comprises: three-phase stator windings; a rotor having 2n magnetic poles (where n is a natural number of 2 or more), a portion of one of the magnetic poles having a magnetic property different from that of said one magnetic pole; three detection devices disposed in the vicinity of said rotor, the detection devices being responsive to a magnetic field generated by the magnetic poles and the portion; first to third amplifiers for amplifying respectively the outputs of the three detection devices; first to third subtracting circuits for obtaining respectively the difference of the outputs of two of the first to third amplifiers; an adding circuit for adding the outputs of the first to third subtracting circuits; and a signal circuit for generating a pulse per one revolution of he rotor on the basis of the output of the adding circuit.

Abstract: A vehicle wheel speed sensor incorporated on an axle spindle hub and hub cap assembly of the type using permanent magnets to generate a magnetic field having a magnetic path conducted through a plurality of teeth on a flange extending from the hub cap into a plurality of teeth on a stator with relative motion therebetween upon rotation of the wheel where the frequency of the change in the magnetic reluctance varies at a frequency proportional to the wheel speed. The stator is mounted to the end of the axle spindle by a securing bolt so that the stator can be easily removed for service without disturbing the axle bearings. As a part of the stator assembly, a locating plate is provided which allows the operating gap between the teeth formed in the flange and the teeth formed in the stator to be easily established upon assembly of the hub cap to the wheel hub by allowing the rotor to contact the locating plate when the hub cap securing bolts have been loosened and the axle is supported.

Abstract: A vehicle wheel speed sensor of the type using permanent magnets to generate a magnetic field having a magnetic path which is conducted through a plurality of teeth on a rotor into a plurality of teeth on a stator with relative motion therebetween where the frequency of the change in the magnetic reluctance varies at a frequency proportional to the wheel speed. The stator is mounted to the end of the axle spindle by way of a securing bolt so that the stator can be easily removed for service without disturbing the axle bearings. As a part of the stator assembly, a locating plate is provided which allows the operating gap between the rotor and the stator to be easily established upon assembly of the hub cap to the wheel hub by allowing the rotor to contact the locating plate when the hub cap securing bolts have been loosened and the axle is supported.

Abstract: The object of the present invention is to obtain a motor capable of producing a large torque and operating with good efficiency in a high-speed region. A reluctance type motor according to the present invention, when one armature coil (32a) is deactivated through one switching element connected to a negative voltage terminal, prevents the magnetic energy stored in the magnetic core from returning to the electric power source by means of a back-flow preventing diode (21a). The magnetic energy is used to charge a small-capacitance capacitor (47a) to hold it to a high voltage. Thus, a trailing-off of current becomes steep. After a predetermined time has elapsed, a next armature coil (32e) is activated. As an applied voltage is a high voltage charged in the capacitor, the exciting current builds up sharply. Since the building-up and the trailing-off of the exciting current of the armature coil can be made sharp, the rotational speed can also be increased up to several 10 thousand rpm.

Abstract: An electrical machine includes a motor having a motor housing and a stator and a rotor received in the housing, and a device for detecting rotor position and rotational speed disposed outside the motor housing on a motor shaft carrying the rotor, the device being fixed to the motor housing.

Abstract: A gear motor having an output shaft for driving the dispensing mechanism of a vending machine includes a plurality of magnetically operated switches positioned adjacent one end of the output shaft and a plurality of magnets attached to that end of the output shaft. A DC electric motor is energized by a computer to rotate the output shaft in a first direction until one of the magnetic switches is actuated by a magnet, which instructs the computer to reverse the polarity of power to the DC motor, reversing the direction of the motor and the output shaft. When the output shaft is returned to its standby position, one or more of the switches are again actuated which instructs the computer to terminate power to the DC motor. An enclosure surrounds the switches and magnets and protects them from the ambient.

Abstract: A commutator employs superconducting switches to commutate currents in the field stator of a dc machine. The switches couple the machine's stator windings to a DC link. The switches are exposed to magnetic fields of alternating strengths, turning on and off in a sequence that maintains a constant torque angle between the stator's mmf vector and the flux vector of the machine's rotor or that rectifies a current induced into the stator by the machine's rotor.

Abstract: A switched reluctance motor (10) provides position and speed detection without a shaft position sensor. At least one of the stator pole faces (54) and/or at least one of the rotor pole faces (60) has an irregularity such as a notch (52 and/or 58) providing a perturbation or blip (70, 82) in the inductance profile (72, 76, 84) of the motor (10) during rotation of the rotor (14) indicative of the position of the rotor (14) relative to the stator (12). The frequency of the perturbations indicates motor speed.

Abstract: A substantially C-shaped core which is used in a rotational position sensor of an inductance type. The core is formed of a sensing side portion and a referencing side portion, each of which has an arc shape. The centers of the arc shapes are spaced apart from one another at a predetermined distance, thereby extending a movable range of a movable short ring. As a result, a rotational position can be detected over a wider range of degrees. The core is also formed of a core intermediate portion, which has laminated thin plates therein, and core opposite end portions, which are disposed in a sealed state on the top and bottom surfaces of the core intermediate portion. The core intermediate portion and the core opposite end portions are welded together at given points so as to form a one-piece body. Surfaces of the core can thereby be prevented from being deformed or detached.

Abstract: A spindle motor able to reduce leaking of magnetic flux of an index magnet to a magnetic head of a disc apparatus. In an axial gap type spindle motor having a rotor case rotatably supported by a base plate, an index magnet is provided to a face of the rotor case opposite to the base plate. A hall device is provided in an open space between a plurality of coils arranged radially on the base plate at a position opposite to the index magnet. A magnetic flux forms a closed loop by passing through the rotor case, and thus leaking of magnetic flux to the outside is reduced.

Abstract: A scanning motor having a bracket, a shaft member secured to the bracket, a rotor rotatably supported by the shaft member via a pair of bearings and a polygonal mirror fastened to the rotor, the polygonal mirror being disposed at a position on the outside of either of a pair of the bearings. The rotor has a rotor body and a yoke member which constitutes a balance adjusting groove in cooperation with a frequency generating magnet fastened to the yoke member. A motor having a bracket, a rotor, magnetic force generating means disposed in the bracket, magnetic flux changing means fastened to the rotor, sensing means for sensing change in the magnetic flux taken place in a magnetic circuit constituted by the magnetic force generating means and the magnetic flux changing means and a covering member for covering the magnetic force generating means.

Abstract: Detector of angular position comprising a stator (1) and a toothed rotor (3) in relative rotation. The stator (1) has magnetoresistors (M1 through M8) in pairs and preferably numbering four or a multiple of four. The magnetoresistors in each pair are almost diametrically opposed and in electrical phase opposition to eliminate magnetic torques on the rotor (3). The use of at least two pairs allows a useful signal to be easily obtained for all angles if the signals of the pairs are out of phase at a 90.degree. electrical angle. The detector provides a very high degree of precision, strength and low energy consumption.

Abstract: A step motor which comprises a stator having a winding wound therearound, a rotor rotatably provided with respect to the stator, a multiplicity of pole teeth formed on mutually opposing faces of the stator and rotor, a position detector for detecting a position of the rotor, and switching means for changing over a phase current flowing through the winding wound around the stator on the basis of a position signal indicative of the position of the rotor, wherein the pole teeth and a position detectable portion are integrally formed on a rotary yoke of the rotor and the position detectable portion is detected by the position detector.