Abstract: A fan motor having a structure which allows a stopper to keep contact with a thrust plate on a circular contact area only, by inserting a shaft through a sleeve bearing, and by attaching the stopper, against the thrust plate, onto the end portion of the shaft. This assures uniform sliding of the thrust plate against the sleeve bearing without partial contact, even if the stopper is attached in a slight inclination with respect to the thrust plate. Localized wear of the thrust plate and rubbing mechanical noise are thus prevented.

Abstract: A micropump comprises a pump body member for defining a tank chamber holding liquid, a liquid inlet portion, a liquid outlet portion for discharging the liquid medium in the tank chamber, a liquid outlet portion for discharging the liquid medium in the tank chamber, and an actuator for reducing a volume of the tank chamber. The actuator is formed of a liquid-absorptive polymer gel.

Abstract: A spindle motor having a housing, a hub member rotatable relative to the housing, a bearing 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 is provided at a position outward of the bearing, and includes a conductive plate for grounding static electricity. The bearing is comprised of a radial ball bearing, which includes certain improvement.

Abstract: An annular recess is formed in a base which constitutes a disk chamber, and an armature constituting a spindle motor for driving a hard disk and composed of a stator core and a stator coil and a field device composed of a rotor yoke and a rotor magnet are substantially accommodated in the annular recess. As a result, the height of a portion of a hard disk apparatus which constitutes a radial directional gap type spindle motor can be minimized and therefore the overall height of the apparatus can be minimized. Hence, the thickness and the size of a computer apparatus or the like which includes the hard disk apparatus can be reduced.

Abstract: A spindle motor comprising a bracket, a hub which is rotational relative to the bracket, and bearing means disposed between the bracket and the hub, wherein the hub has a hub main body made of aluminum or an aluminum alloy, and a holder formed from a magnetic material, and wherein a rotor magnet is mounted on the inner surface of the holder. A ring-shaped recess is provided on the inner surface of the bracket, and the hub and a part of the rotor magnet extend into the ring-shaped recess. Improvements having been made on a disk clamp mechanism for mounting a recording disk on the hub of the spindle motor.

Abstract: A magnetic recording device exhibiting reduced electromagnetic interference has a magnetic recording medium, a spindle motor for rotationally driving the magnetic recording medium, a magnetic head for writing and/or reading magnetic information and a shifting device for shifting the magnetic head. A stator core is provided with nine pole pieces divided into three groups of adjacent pole pieces. Each group of three adjacent pole pieces is wound with one of three different 3-phase coils such that adjacent pole pieces in a group have opposite polarities relative to a rotor magnet. The magnetic head is disposed corresponding to a specific slot of a stator core in the spindle motor. A shift route thereof extends outwards virtually in the radial direction from the specific slot.

Abstract: A micropump comprises a housing for defining a pump chamber, an inlet valve disposed in an inlet flow passage, a outlet valve disposed in a outlet flow passage, and an actuator for changing a volume of the pump chamber. The actuator is formed of a thermo-responsive polymer gel material. Fluid is supplied and fed by heating and cooling the actuator.A micropump comprises a pump body member for defining a tank chamber holding liquid, a liquid inlet portion, a liquid outlet portion for discharging the liquid medium in the tank chamber, a liquid outlet portion for discharging the liquid medium in the tank chamber, and an actuator, for reducing a volume of the tank chamber. The actuator is formed of a liquid-absorptive polymer gel.

Abstract: A magnetic disk drive device has a spindle motor for rotatingly driving magnetic disks in a predetermined direction, and a clamp member for mounting the disks on the spindle motor. The spindle motor has a hub rotatably supported through bearings and having a portion for mounting the magnetic disks, a rotor magnet carried by the hub, a stator disposed to oppose to the rotor magnet, and magnetic fluid seal arrangement for preventing scattering of lubricant from the bearing means. The magnetic disk drive device further has a magnetic shield disposed on the radially outer side of the magnetic fluid seal arrangement. One of the bearings rotatably supporting the hub may be charged with a lubricant having a comparatively low viscosity, while the other bearing may be charged with a lubricant having a comparatively high viscosity.

Abstract: A spindle motor comprises a housing, a hub which is rotatable relative to the housing, a rotor magnet mounted on the hub, and a stator disposed facing the rotor magnet. A coil holding member for extending a lead section of an armature coil of the stator to the outside thereof is disposed in the housing. Female screw holes into which fixing screws for mounting clamp members are screwed and through holes connecting with the female screw holes are formed in the hub. Furthermore, supporting projections extending toward the housing are disposed in the stator core of the stator, and such supporting projections are supported in the housing.

Abstract: A spindle motor comprises a housing, a hub arranged for rotation on the housing, a couple of bearings interposed between the housing and the hub, a rotor magnet mounted to the hub, and a stator mounted to the housing so as to face the rotor magnet, in which at least one of the two bearings is of single seal type having a seal at one side. Also, a flexible pc film is provided for supply of electric energy to the stator and arranged for improved connection to an armature coil of the stator.

Abstract: A torque transducer including: a ferromagneto-stricting device provided for a rotational shaft; a magnetic field supply device for supplying a magnetic field to the ferromagneto-stricting device; a sensing device for sensing the change in the magnetic permeability which has taken place due to torque acting on the rotational shaft; a fixed housing for rotatably supporting the rotational shaft via a bearing unit; and an electromagnetic shielding device for surrounding the magnetic field supply device and the sensing device to electromagnetically shield them. The magnetic field supply device comprises an exciting coil, while the sensing device comprises a sensing coil. The electromagnetic shielding device is supported by the fixed housing via an elastic holding member. A seal member is disposed outside the bearing unit. The fixed housing and the electromagnetic shielding device are electrically earthed.

Abstract: There is provided a drive control apparatus for a motor having a drive device for controlling current supplied to an armature coil, a control device for controlling the rotation speed of a rotor, and a mode switch device for comparing a rotation speed signal and a predetermined reference voltage and generating a normal rotation mode signal or a reverse rotation mode signal. Furthermore, the drive control device has the drive device, the control device and a signal delay device. The signal delay device delays the supply of a stop signal from the control device by a predetermined time, and a reverse current is supplied to the armature coil during the delay time.

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: A driving control circuit of a motor having a sensorless 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 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 charging control circuit having a controller including a microcomputer, a charging circuit, detectors for detecting the voltages between the terminals of batteries, and memories for storing charge control data. The controller determines that quick charging is completed when the voltage between the terminals of each battery drops from a peak value to an extent corresponding to a predetermined value stored in the memory, and then terminates the charging operation. During a predetermined period of insensible time immediately after the start of charging stored in the memory, the controller does not detect the voltage to determine whether or not each battery is fully charged, thereby preventing an error in determining a fully charged state of the battery. If a full charge of each battery is not detected while quick charging is continued for a certain period of time stored in the memory, the controller forcibly terminates the quickly charging operation.

Abstract: Starting, accelerating and rated rotation of a rotor is carried out without any detector for the rotor position. A motor is controlled with an openloop circuit a short time in a starting area of low speed rotation, and thus the motor can be certainly started. In a rated rotation area, turning timing of the motor is precisely controlled by detecting counter-electromotive force of a stator coil.

Abstract: A spindle motor has a stationary member, a hub rotatable relative to the hub, a stator mounted on the stationary member and a rotor magnet carried by the hub and facing the stator. The hub is provided with female-threaded holes for receiving screws for fixing a disk clamp member to the hub, and also with communication holes communicating with the female-threaded holes and opening to the exterior of the hub. The hub further has a seal member for sealing the openings of the communication holes. The hub is rotatably supported by the shaft member through a pair of bearings. The stator has a stator stack of a stack height or thickness greater than the spacing of the pair of bearings.

Abstract: A magnetic disk drive device has a spindle motor for rotatingly driving magnetic disks in a predetermined direction, and a clamp member for mounting the disks on the spindle motor. The spindle motor has a hub rotatably supported through bearings and having a portion for mounting the magnetic disks, a rotor magnet carried by the hub, a stator disposed to oppose the rotor magnet, and magnetic fluid seal arrangement for preventing scattering of lubricant from the bearing means. The magnetic disk drive device further has a magnetic shield on the radially outer side of the magnetic fluid seal arrangement. One of the bearings rotatably supporting the hub may be charged with a lubricant having a comparatively low viscosity, while the other bearing may be charged with a lubricant having a comparatively high viscosity.

Abstract: A spindle motor comprises a housing, a hub which is rotatable relative to the housing, a rotor magnet mounted on the hub, and a stator disposed facing the rotor magnet. A coil holding member for extending a lead section of an armature coil of the stator to the outside thereof is disposed in the housing. Female screw holes into which fixing screws for mounting clamp members are screwed and through holes connecting with the female screw holes are formed in the hub. Furthermore, supporting projections extending toward the housing are disposed in the stator core of the stator, and such supporting projections are supported in the housing.

Abstract: A battery charger and a charge controller therefor are disclosed, the battery charger including a supply circuit for supplying a charging current to a battery and a control circuit for controlling the supply of the charging current to the battery. The control circuit shuts the charging current when the detected voltage of the battery is smaller than the maximum peak value by a predetermined quantity. A control means shuts the charging current after a predetermined time has elapsed from a time at which the detected voltage of the battery has raised to the maximum peak value. The control means reduces the charging current when the detected voltage of the battery is made to be a switching voltage. Furthermore, the control means shuts the charging current after a predetermined time has elapsed after the charging current had been reduced.