Abstract: A reverse torque, forward commutation motor driver system for a phased motor rapidly decelerates or “brakes” the motor by exciting, in sequence, a complementary excitation signal in each normal commutation state of the forward state machine, thereby providing an active braking effect. After active braking reduces the rotational velocity of the motor below a threshold, a dynamic braking technique can replace the active braking, wherein high-side drivers are set to an opposite voltage as compared to low-side drivers.

Abstract: A data storage device has a plurality of head/surface combinations with different data track densities on at least two surfaces. A minimum head quality is established for the data storage apparatus. Head quality is identified for each of the heads at each of a plurality of track densities. A tuned track density is selected for each surface based on the track density that corresponds to a head quality.

Abstract: A method and apparatus for reducing retry redundancy during disc read operations in a disc drive system are provided in which a number of physical sectors to be read from the disc during read operations is first determined. An attempt is then made to read all sectors of the number of sectors during a first disc revolution. Failed sectors of the number of sectors during the first disc revolution are also identified. A retry cycle is then performed on the failed sectors during a second disc revolution following the completion of the attempt to read all sectors of the number of sectors during the first revolution.

Abstract: A method and apparatus for detecting and recovering from head instability in a magneto-resistive (MR) transducer head of a disc-drive system. A head-instability-recovery circuit is described for use in disc drive to recover from a head-instability condition of an MR transducer head. This circuit includes a controller and a current source that supplies current to the MR head. The current source is controlled to supply a nominal amount of current to the MR head when operating in a normal mode, and to supply one or more current bursts having a current above the nominal supply current in order to recover from the head-instability condition. Also described is a method for recovering from a transducer-instability condition of an MR transducer of a disc drive, including detecting a situation that indicates a head-instability-recovery operation is desired, and performing the head-instability-recovery operation.

Abstract: A method for minimizing unbalance in the disc pack of a disc drive where the unbalance of the spindle motor is quantified and incorporated into the biasing assembly of the disc pack. In the assembly process, the discs are biased in a manner such that the unbalance of the spindle motor is considered.

Abstract: A magnetless rotary actuator for carrying one or more read/write heads across a data bearing medium, the rotary actuator comprising: a stator including a plurality of independently controllable flux generating means for directing flux between the stator and a rotor; the rotor including means for presenting discrete regions of low magnetic reluctance to the controllable flux generating means; torque coupling means for transmitting operative torque from the rotor to the read/write head; and pivot means for supporting the torque coupling means.

Abstract: A method sets bit densities and track densities for a plurality of heads in a data storage device. The method includes determining an initial bit density and an initial track density for each head. An initial total capacity for the storage device is determined based on the initial track densities and the initial bit densities. A desired capacity for the storage device is selected and the initial total capacity and the desired capacity are compared. One of either a bit density or a track density is then adjusted so that the data storage device has an adjusted capacity that provides some excess capacity over the desired capacity where the excess capacity is less than any excess capacity that was present between the initial capacity and the desired capacity. A data storage device formed through this method is also provided.

Abstract: A process of run-time temperature compensating bias current to a magnetoresistive read head in which a plurality of temperature ranges are defined with associated bias current values. A hysteresis range of temperatures is defined for each boundary between temperature ranges. A bias current value is selected based on the temperature range of the sensed temperature. The process is repeated. If the sensed temperature is in a different temperature range from that previously identified and the measured temperature is not in a hysteresis range at the boundary with the temperature range previously identified, the selected bias current value is based on the presently identified temperature range. If the sensed temperature is in a hysteresis range at the boundary with the temperature range previously.

Abstract: A method for minimizing unbalance in the disc pack of a disc drive where the unbalance of the spindle motor is quantified and incorporated into the biasing assembly of the disc pack. In the assembly process, the discs are biased in a manner such that the unbalance of the spindle motor is considered.

Abstract: A method and apparatus for reducing retry redundancy during disc read operations in a disc drive system are provided in which a number of physical sectors to be read from the disc during read operations is first determined. An attempt is then made to read all sectors of the number of sectors during a first disc revolution. Failed sectors of the number of sectors during the first disc revolution are also identified. A retry cycle is then performed on the failed sectors during a second disc revolution following the completion of the attempt to read all sectors of the number of sectors during the first revolution.

Abstract: A method sets bit densities and track densities for a plurality of heads in a data storage device. The method includes determining an initial bit density and an initial track density for each head. An initial total capacity for the storage device is determined based on the initial track densities and the initial bit densities. A desired capacity for the storage device is selected and the initial total capacity and the desired capacity are compared. One of either a bit density or a track density is then adjusted so that the data storage device has an adjusted capacity that provides some excess capacity over the desired capacity where the excess capacity is less than any excess capacity that was present between the initial capacity and the desired capacity. A data storage device formed through this method is also provided.

Abstract: A magnetless rotary actuator for carrying one or more read/write heads across a data bearing medium, the rotary actuator comprising: a stator including a plurality of independently controllable flux generating means for directing flux between the stator and a rotor; the rotor including means for presenting discrete regions of low magnetic reluctance to the controllable flux generating means; torque coupling means for transmitting operative torque from the rotor to the read/write head; and pivot means for supporting the torque coupling means.