Abstract: A heat sink fan has a fan motor provided with blades, a rectangular upper casing for holding the fan motor, and a rectangular lower casing fixed to the upper casing. The lower casing has a bottom portion and fin dissipating fins erected perpendicularly from the four side edges of the bottom portion. The upper and lower casings are fixed together by a mechanically interlocking mechanism consisting of a combination of pawls and pawl receiving portions, a combination of projections each having an inflated portion and cavities or a combination of hooks and engaging grooves formed or in the upper or lower casing. Fin portions are formed on the whole area or the area except for the fan motor and the blades to increase a heat dissipating efficiency.

Abstract: For charging a storage battery, e.g. a nickel-cadmium cell, recharging is conducted after the battery is forcibly discharged while the charge voltage stays in a specified range after a period of time from the start of the charging action. Accordingly, the generation of memory effect will be avoided. The charging will successfully be carried out without declining the storage capacity of the battery. In both charge and adaptor modes, output voltage and current are examined whether the battery is coupled correctly or not and if not, their delivery is canceled with producing an alarm display. As the result, the charging to the battery and the power supply to an external electric appliance will be implemented without error.

Abstract: The inner wall of a hub has a step surface between an upper bearing mounting surface and a magnet mounting surface. A spacer of ring-like shape is directly mounted to the step surface of the hub for determining the upper position of a rotor magnet. The inside diameter of the spacer is smaller than the inner wall at the bearing mounting surface of the hub so that a space is created between the bearing mounting surface, the spacer, and the bearing for holding a portion of adhesive. When a portion of the adhesive applied for bonding the bearing to the bearing mounting surface of the hub remains uncured, it will be retained in the space and prevented from entering the interior of the motor.

Abstract: A spindle motor comprises a rotary sleeve; a rotor hub which is integrally rotated with the rotary sleeve; a stationary sleeve; and a stationary support extending upwardly from the stationary part, the rotary sleeve being fitted onto the outer peripheral surface of the stationary support, and radial and thrust hydrodynamic bearings being provided on the relative sliding surfaces of both rotary sleeve and stationary support. A pair of annular grooves which partially overlap each other in the axial direction are peripherally provided on the rotary sleeve and stationary support, thereby providing a labyrinth chamber to suppress the outflow of the lubricant.

Abstract: A low airflow hard disk apparatus comprises a base, a cover member, a rotational portion disposed in a disk chamber, a hard disk held by and rotatable with the rotational portion, a first projection portion disposed on the lower surface of the cover member and facing toward the upper surface of the hard disk, and a second projection portion disposed on the upper surface of the base and facing toward the lower surface of the hard disk. The first and second projection portions, preferably radially extending fins, prevent an air flow from generating by the rotation of the hard disk.

Abstract: A spindle motor, a hub member for carrying a recording disk(s) thereon, a shaft member fixedly mounted to the hub member, and a bracket member rotatably supporting the shaft member. A pair of bearings each have inner and outer races fixed respectively to the bracket member and the hub member. First and second annular recesses relieve pressure on the bearings and also carry adhesive fixing the beatings in position.

Abstract: A fan motor has a pair of ball bearings placed in the vicinity of each end of an inner side of a bearing race. A plurality of projections are sequentially placed circumferentially around a center portion of the bearing race to axially locate both the ball bearings. A plurality of low-profile projections are sequentially formed between neighboring projections on the inner side surface of the bearing race and are axially elongated from one installing position to that of another installing position of respective ball bearings. The ball bearings are supported by the inner side of each low-profile projection respectively at one end portion and the other end portion of the low profile-projections.

Abstract: A driving control circuit of a sensorless motor having a stator and a rotor, used for a magnetic disk device, comprising a high-frequency stepping oscillator, stepping oscillator, a timer, a stepping timing generating circuit, a current switching logic, an output driver, and a counter electromotive force detecting circuit, wherein three-phase driving coils are connected to an output driver. For starting, a high frequency stepping step a holding step where current flow conditions are held without switching currents to the driving coils, are executed; then, currents to the driving coils are inverted to obtain a reversed excited condition; and, after performing a stepping step for starting the motor is controlled at a steady rotating speed by detecting counter electromotive forces.

Abstract: A disk drive apparatus in which a hard disk is fitted on a disk-fitting outer peripheral portion of a rotor hub. A gap is defined on the outer periphery of the rotor hub such that the axial height of the gap decreases radially inward. An elastic ring member, which is appropriately tensed in the circumferential direction, fits in the gap so as to exert a contracting force which serves to clamp the hard disk between itself and a disk supporting surface. The hard disk can be securely and easily fixed to the rotor hub with uniform application of the clamping pressure over the entire circumference, even when the axial height of the whole disk drive apparatus is reduced.

Abstract: A transformer including a bobbin having a primary winding frame and a secondary winding frame, a primary coil wound around the primary winding frame, a secondary coil wound around the secondary winding frame, a pair of connection pins electrically connected to a power source. A projection which can be broken or bent is provided on the bobbin. The wire of the primary coil is hitched over the projection and then wound to form the primary coil, and the projection is therafter broken or bent to loosen the primary coil. A discharge means is also provided to cause a discharge between the pair of connection pins when a high voltage is applied therebetween.

Abstract: A spindle motor comprising a stationary member, a hub rotatably supported on the stationary member via a pair of bearing members, and a magnetic fluid seal disposed outwardly of at least one of the pair of bearing members. A passageway or conduit hole is provided to conduct between an annular space separated by the stationary member, the magnetic fluid seal means, the rotor and the other of the bearing member and the inside of the motor. Furthermore, a magnetic fluid holder in the magnetic fluid seal is provided.

Abstract: A method of starting a motor comprising a first starting step of supplying an exciting current to armature coils, a first holding step for holding the exciting current after the first starting step, a second starting step of supplying an exciting current to the armature coils after the first holding step, a second holding step of holding this exciting current after the second starting step, and a third starting step of supplying an exciting current to the armature coils after the second holding step. In this method, the frequency f.sub.1 of the first holding step is larger than the characteristic frequency F.sub.0 of the rotation system of the motor (f.sub.1 >F.sub.0) and the frequency f.sub.2 of the second holding step is smaller than the characteristic frequency F.sub.0 of the rotation system (f.sub.2 <F.sub.0).

Abstract: A spindle motor having a housing, a hub member rotatable relative to the housing, a bearing means disposed between the housing and the hub member, a rotor magnet mounted on the hub member, and a stator disposed in a facing relationship with the rotor magnet. The hub member includes a supporting wall portion, which cooperates with the stator to constitute an air seal structure. A magnetic fluid seal means is provided at a position outward of the bearing means, and includes a conductive plate for grounding static electricity. The bearing means is comprised of a radial ball bearing, which includes certain improvement.

Abstract: A spindle motor comprises a stationary member, a hub which is mounted rotatably on the stationary member through a pair of bearings, a rotor magnet which is mounted on the hub, a stator located face to face to said rotor magnet and a clamp for mounting recording disks to the hub. The hub is provided with a mating protrusion for fixing the clamp, the mating protrusion is fitted with a flat end of the hub, and the clamp is fixed by mounting the flat end of the hub with a fastening screw. Further, with a sealing member being fitted on the bearing, a labyrinthine sealing structure is formed with the sealing member and the stationary member.

Abstract: A motor eccentricity measuring apparatus is provided comprising a detecting device for detecting a deflection of the rotating shaft of a motor, a first, a second, and a third hold device for holding detected values supplied from the detecting device, and an amplifier device for amplifying a difference between two outputs of the first and the second hold device. In operation, RRO is calculated, during a first measuring period, from the detected values of the first and third hold device and NRRO is calculated, during a second measuring period, from the detected values of the first and second hold device and simultaneously, amplified with the amplifier device.

Abstract: A motor is provided which includes a housing, a stator attached to the cylindrical wall of the housing, a sleeve bearing attached to the inner periphery of the cylindrical wall, a rotor rotatably supported by the sleeve bearing, and a rotor magnet attached to the rotor. A plurality of projecting strips are formed substantially at equal intervals on the inner and/or outer periphery of the cylindrical wall of the housing. The cylindrical wall is formed into a shoulder and a mating recess. The stator has elastic pieces. Because of the operation of the elastic pieces, the stator is elastically retained between the shoulder and the mating recess. Circuitry for protecting the motor is improved.

Abstract: A circuit and a method of driving a DC motor is provided in which a DC power to be supplied to the DC motor is oscillated in phase for producing a variable torque. As the torque is varied, its peak value increases while its average remains unchanged. Hence, the maximum torque needed for starting rotation will successfully be obtained. Once the rotation starts, a lower torque is accepted for continuous rotation of a load. The rotation can thus be conducted by a lower amplitude of the variable torque. Accordingly, when the rotating torque of the motor becomes low due to increase in unwanted load or declination in capability, the motor can remain operable without troublesome repair or replacement.

Abstract: A DC motor having a housing, a hub member rotatably supported by the housing, a flexible printed circuit board fixedly mounted on the housing, and an IC chip mounted on the flexible printed circuit board and located facing a recess formed in the housing. The hub member has a shaft rotatably supported by a bearing within the recess. The flexible printed circuit board has a metal layer for mounting the IC chip, the metal layer being isolated from a wiring pattern formed on the printed circuit board. The wiring pattern on the flexible printed circuit board is directly connected to a connection pin connected to the motor wiring.

Abstract: A brushless polyphase DC motor is applied to a spindle motor for a disk device and has a stator generating a magnetic field in an excited state and a rotor obtaining turning force by the electromagnetic interaction with the stator. When an electrical charge current is intermittently and alternately supplied to the coil of the stator in opposite directions, for example, if electrical charge is stopped after current in the normal direction is supplied, a residual magnetic field density is generated in the stator during the stopping period. The residual magnetic flux density is employed for performing electrical charge in the reverse direction by supplying current in the reverse direction. In this case, a high torque is generated by increasing a change in the magnetic flux density.

Abstract: A spindle motor comprises a stationary member, a hub for rotation relative to the stationary member, bearings provided between the stationary member and the hub, and a labyrinth seal provided outside one of the bearings. In particular, the labyrinth seal includes a plurality of labyrinth units. Each labyrinth unit is consisted mainly of a first member mounted to the stationary member and a second member mounted to the hub.