Abstract: A system and method for unloading a transducer assembly to a ramp positioned outside an outer diameter of a disc in a disc drive system directs current generated from the back EMF (electromotive force) of a spindle motor to supplement current provided by a power supply to a positioning coil. The combined current yields increased torque to park the transducer assembly without requiring unnecessary power consumption during normal disc drive operation. The current generated from the back EMF of the spindle motor is enhanced by accelerating the rotation of the spindle motor to exceed the normal operational rotational velocity of the disc drive system. A position detector provides a trigger signal to control the timing of the switch that combines the current from the back EMF and the current from the power supply to the positioning coil.

Abstract: For low velocity retraction of a disc drive actuator during a parking operation, a system comprising a voltage generator circuit generates a plurality of discrete dc voltage levels, a timing circuit provides a series of timing pulses, and a selection circuit responsive to the voltage generator and timing circuit outputs a voltage profile of increasing voltage steps from the voltage levels and the timing pulses. The voltage profile is provided to a driver circuit that drives a voice coil motor which, in turn, positions the actuator with respect to the discs of the disc drive. The application of the voltage profile during the parking operation causes the driver circuit to act as a voltage source for the voice coil motor. External bias forces upon the actuator tending to force the actuator towards the park position generate a back EMF in the coil, opposing the voltage source of the driver circuit and the motion of the actuator towards the park position.

Abstract: A narrow read head and a wider write head are used to store and retrieve data from a storage medium, such as a magnetic disk or tape. The wider write head is selectively positioned to record overlapping data tracks. The read head is subsequently positioned to read the non-overlapping portions of the data tracks. In one format, a read seldom data block is recorded by sequentially recording a plurality of data tracks such that each subsequent data track partially overlaps a previously written data track. In another format, pairs of data tracks are recorded by side-by-side, wherein within each pair of data tracks there is an overlapping region. In either format, the narrower read head is positioned to read the non-overlapping portions of the data tracks. Consequently, the storage capacity of the storage medium is optimized to take advantage of the narrow read head.

Abstract: The method disclosed is generally directed to a process for controlling the velocity of an actuator arm assembly during a load from a ramp. A process in accordance with the invention includes applying an alternating current to the VCM to eliminate frictional effects. An increasing current is applied to the VCM. The increasing current is an increasing function of time in one embodiment of the invention and is determined such that the heads are loaded at a predetermined velocity. In one embodiment, the predetermined velocity is 1 in/sec.

Abstract: A direct access storage device (DASD) employs a servo including a digital signal processor having a software switch (DSP). The DSP is provided with DSP code in a DSP code space. One of the functions of the DSP code is to implement the microstep calibration of the present invention. Microstep calibration is accomplished by a step change of head position within a single track. In head position 1 the head is at the center of the track in track follow mode. From head position 2 to head position 3, an offset command causes the servo to move the head slightly off center. From head position 3 to head position 4, the servo is disabled by opening the software switch in the DSP. The position delta, delta 3-4, of the head is recorded. From position 4 to position 6, the servo is still disabled and a step of current is applied to the VCM to determine position delta 2. From position 7 to position 8, the servo is still disabled and two steps of VCM current are applied to recover to the offset position.

Abstract: A direct access storage device (DASD) employs a servo including a digital signal processor having a software switch (DSP). The DSP is provided with DSP code in a DSP code space. One of the functions of the DSP code is to implement the microstep calibration of the present invention. Microstep calibration is accomplished by a step change of head position within a single track. In head position 1 the head is at the center of the track in track follow mode. From head position 2 to head position 3, an offset command causes the servo to move the head slightly off center. From head position 3 to head position 4, the servo is disabled by opening the software switch in the DSP. The position delta, delta 3-4, of the head is recorded. From position 4 to position 6, the servo is still disabled and a step of current is applied to the VCM to determine position delta 2. From position 7 to position 8, the servo is still disabled and two steps of VCM current are applied to recover to the offset position.

Abstract: A rotary unit such as a disk file, retained in a dynamically balanced condition. In each end of the unit, there is an annular channel concentric with the rotational axis encircled by a flexible rim. A plurality of balls of substantially identical size and weight are inserted in an outer portion of each channel in which the balls are freely movable. While the unit is rotated at a speed above resonance, a balancing instrument is used to determine the mass magnitude and angle necessary to dynamically balance the unit. Then the balls are circumferentially relocated by vector balancing to provide mass at points equivalent to the determined mass and angle. The relocated balls are then forced axially past an interference ridge and into an inner portion of the respective channel in which the rim is flexed and the balls are held against movement.

Abstract: The start-up of a rotating disk file is controlled by first moving the sliders (30, 32, 40, 42) supporting the read/write heads radially outwardly from the inside diameter (20) of the disks (10, 12, 14) by applying a voltage from voltage source (70) to voice coil motors (34, 44), sensing the position of the sliders (30, 32, 40, 42) on the disk surfaces with a position sensor (80), initiating rotation of the disk drive motor (18) when the sliders (30, 32, 40, 42) have moved a dewetting distance, and terminating radial translation of the sliders (30, 32, 40, 42) when the disk drive motor (18) has reached operating speed and the sliders (30, 32, 40, 42) are riding on a bearing of air above the disk surfaces. The instrumented radial translation of the sliders (30, 32, 40, 42) overcomes the stiction forces at the slider-disk interface without damage to the read/write heads, the disks (10, 12, 14) or the slider suspensions (36, 38, 46, 48).