Abstract: A low speed moving magnet motor (1) has a moving magnet (10) and a stationary coil (20) for carrying an electric current and disposed in relation to the moving magnet (10) such that a magnetic field generated when a current flows through the coil (20) causes the moving magnet (10) to move relative to the coil. A magnetic return path member (15) is fixed in relation to the coil (20) to provide a return path for a magnetic field generated by the coil (20) and the moving magnet (10). In an example, the magnetic return path member (15) is free of insulating laminations. The moving magnet (10) is mounted on a rotor (6) of the motor (1) which has a high inertia.

Abstract: A vibration damping system is provided for damping vibrations in an apparatus (1). The damping system is particularly useful in a servowriter (1). The damping system has resilient means (7) for supporting at least the majority of the weight of the apparatus (1). The resilient means (7) has a first spring rate. The damping system has damping means (8) for damping vibrations of the apparatus (1). The damping means (8) has an effective second spring rate. The ratio of the first spring rate to the effective second spring rate is r:1 where r<1.

Abstract: A tool (20) is provided for mounting in and testing a fixture (12) used for mounting a device, such as a disk drive, having an arm which is movable to selected locations by an actuator. The tool has a movable member (25) which is movable to mimic movement of an arm of such a device mounted in the fixture (12). Movement of the tool (20) in the fixture (12) as a reaction to movement of the movable member (25) is measured and compared with a standard to enable the fixture to be passed or failed.

Abstract: A mounting for a disk file comprises a carrier defining a space into which the disk file can be removably inserted for operational use. The carrier has a base and two opposed sides and, and first and second wedges and which are movable to act between the main body of the disk file and the side of the carrier, to secure the disk file against movement relative to the carrier. The wedges include wedges which are movable in a vertical direction by a control linkage operated automatically when the disk file is inserted into the carrier structure.

Abstract: A disk file has a frame with a non-rotatable shaft (2) extending in an axial direction between opposed wall portions of the frame. The shaft is clamped at one end to the frame by a screw (8) passing through an opening in the wall and axially into the shaft. This arrangement is susceptible to tilting of the shaft due to differential thermal expansion if the frame wall (1) and the shaft have dissimilar coefficients of thermal expansion. A bush (9) is located between the screw and the shaft. The bush is held in the wall by an interference fit, and has a coefficient of thermal expansion similar to that of the shaft. The inclusion of the bush greatly reduces problems due to differential thermal expansion.

Abstract: A disk file includes multiple disk surfaces, on which servo information is recorded, with an offset in azimuth from one disk surface to another. Each head comprises a magnetoresistive stripe for reading and an inductive write coil. The servo system reads servo information from each disk in turn, multiplexing the signals from each disk together to form a single position error signal (PES). The separation of the servo multiplexer, attached to the MR stripes, from the write multiplexer, attached to the inductive coils, avoids problems due to contamination of the servo signal by the write signal. A least squares fit is used to generate the PES from the series of servo samples from each disk surface.

Abstract: A disk file includes an expansion ring attached to the wall of the hub and which is located between the lowermost disk of the disk stack and the hub flange. A circular ridge concentric with the hub is formed on the ring and engages the underside of the disk. The ring is adapted so that the thermal expansion of the ring is substantially equal to that of the aluminum disk at the position of contact between the two. A washer interposed between ring and flange allows the ring to move freely relative to the flange. During thermal cycling, the ring and disk move at the same rate at the point of contact, the ring ensuring that the disks remain concentric with the hub throughout the range of disk file operating temperatures.

Abstract: A method of assembling a disk file comprises merging a pre-assembled actuator assembly and disk stack assembly prior to attaching them to a common base. The relative axial positions of the actuator assembly and disk stack assembly are measured and adjusted to align head arms with collapsed suspensions with the inter disk spaces. Once aligned the two assemblies can be moved together and the heads released.

Abstract: A voice coil actuator comprising a carriage assembly and a magnet assembly includes a cylindrical shorted turn resiliently mounted in the magnet assembly. The shorted turn is thereby allowed limited movement in a direction parallel to its own axis. In this way, the reaction force on the magnet assembly, caused by the movement of the carriage assembly during operation of the actuator, can be absorbed by the shorted turn.

Abstract: A disk file comprises a head disk enclosure 1 connected to a support frame by a plurality of isolation mounts. Each isolation mount comprises a constrained layer flexure 23 which is rigidly attached at both ends to a bracket 25 of the support frame. Located in an aperture in the constrained layer flexure is a resilient grommet 24. This grommet supports a bolt 27 which passes through the grommet and into the head-disk enclosure casting.

Abstract: A linear actuator for positioning the heads of a disk file relative to tracks on the disks employs a ceramic material having wear properties superior to steel in guide surfaces for guiding a head supporting carriage running on rotary bearings in contact with the guide surfaces. The preferred ceramic material is tetragonally stabilized zirconia.

Abstract: A cantilever magnetic head support arm assembly for a disk file comprises a flat beam structure and a means of damping the structure against out-of-plane vibrations. The damping means comprises a rigid sidebar extending along one longitudinal edge of the beam structure and a layer of compliant damping material connecting the beam structure and sidebar together. Relative motion between the beam structure and sidebar causes elastic shear deformation of the damping layer to absorb the energy of vibration.

Abstract: An electric rotary actuator for producing rotation through a limited angle comprises a rotor winding made of a plurality of thin loop coils arranged in a continuous cylindrical framework as part of a rotor shell. The rotor shell lies in an annular flux gap defined by a stator magnet assembly and a flux return means. Each pair of adjacent axially extending limbs of adjacent loop coils lies opposite to and cooperates with a respective stator pole face. This winding arrangement helps to optimize the torsional resonance characteristics of the rotating mass.