Abstract: Apparatus for protecting a disc drive from damage due to non-operational mechanical shocks, the disc drive including a rotatable disc having an inner radius and an outer radius and a controllably rotatable actuator adjacent the disc. A snubber is provided adjacent the disc, the snubber having a body portion rigidly affixed with respect to the disc and snubber arms connected to the body portion. The snubber arms extend from the body portion towards the disc and above and below the elevation of the disc, with each snubber arm having a distal end located at a position adjacent the disc between the inner and the outer radii of the disc and towards the outer radius of the disc. The height of each snubber arm limits deflection of the disc at the outer radius of the disc as a result of mechanical shock forced supplied to the disc drive assembly.

Abstract: A disc drive is provided with rotatable discs and an actuator assembly having heads adjacent the discs. A flex circuit assembly providing electrical connection between the heads and the disc drive circuitry comprises flex strips routed on the actuator assembly from the heads and a flex affixed on the actuator assembly. A flex support snubber mounted on the side of the actuator assembly has a body portion with a plurality of arms extending therefrom. Each pair of the arms form a groove so that the arms are disposed above and below discs while the discs extend into the grooves. A plurality of slits are interposed between the grooves to support the flex strips therein. An opposite end of the flex support snubber curves to form a U-shaped snubber bend for turning and guiding a dynamic portion of the flex.

Abstract: Apparatus for protecting a disc drive from damage due to non-operational mechanical shocks, the disc drive comprising a rotatable disc having an inner radius and an outer radius and a controllably rotatable actuator adjacent the disc. A snubber is provided adjacent the disc, the snubber having a body portion rigidly affixed with respect to the disc and snubber arms connected to the body portion. The snubber arms extend from the body portion towards the disc and above and below the elevation of the disc, with each snubber arm having a distal end located at a position adjacent the disc between the inner and the outer radii of the disc and towards the. outer radius of the disc. The height of each snubber arm limits deflection of the disc at the outer radius of the disc as a result of mechanical shock forced supplied to the disc drive assembly.

Abstract: Apparatus for protecting a disc drive from damage due to non-operational mechanical shocks, the disc drive comprising a rotatable disc having an inner radius and an outer radius and a controllably rotatable actuator adjacent the disc. A snubber is provided adjacent the disc, the snubber having a body portion rigidly affixed with respect to the disc and snubber arms connected to the body portion. The snubber arms extend from the body portion towards the disc and above and below the elevation of the disc, with each snubber arm having a distal end located at a position adjacent the disc between the inner and the outer radii of the disc and towards the outer radius of the disc. The height of each snubber arm limits deflection of the disc at the outer radius of the disc as a result of mechanical shock forced supplied to the disc drive assembly.

Abstract: Apparatus for protecting a disc drive from damage due to non-operational mechanical shocks, the disc drive comprising a rotatable disc having an inner radius and an outer radius and a controllably rotatable actuator adjacent the disc. A snubber is provided adjacent the disc, the snubber having a body portion rigidly affixed with respect to the disc and snubber arms connected to the body portion. The snubber arms extend from the body portion towards the disc and above and below the elevation of the disc, with each snubber arm having a distal end located at a position adjacent the disc between the inner and the outer radii of the disc and towards the outer radius of the disc. The height of each snubber arm limits deflection of the disc at the outer radius of the disc as a result of mechanical shock forced supplied to the disc drive assembly.

Abstract: An apparatus and method for recovering from read errors detected by a read channel (70) in a sequence of data read from a disc (18) of a disc drive (10) by using read channel quality indicators to determine the appropriateness of using error correction in combination with other corrective actions utilized in the recovery process. Upon the detection of an uncorrected error in the retrieved data, the disc drive (10) enters a read error recovery routine wherein one or more corrective actions (102, 122) are applied in an effort to resolve the error. One of the channel quality indicators comprises a channel quality measurement (108, 128) determined as the sum of the square of the sampled data bit error values recovered during the read operation.

Abstract: Apparatus for protecting a disc drive from damage due to non-operational mechanical shocks, the disc drive comprising a rotatable disc having an inner radius and an outer radius and a controllably rotatable actuator adjacent the disc. A snubber is provided adjacent the disc, the snubber having a body portion rigidly affixed with respect to the disc and snubber arms connected to the body portion. The snubber arms extend from the body portion towards the disc and above and below the elevation of the disc, with each snubber arm having a distal end located at a position adjacent the disc between the inner and the outer radii of the disc and towards the outer radius of the disc. The height of each snubber arm limits deflection of the disc at the outer radius of the disc as a result of mechanical shock forced supplied to the disc drive assembly.

Abstract: Apparatus for protecting a disc drive from damage due to non-operational mechanical shocks, the disc drive comprising a rotatable disc having an inner radius and an outer radius and a controllably rotatable actuator adjacent the disc. A snubber is provided adjacent the disc, the snubber having a body portion rigidly affixed with respect to the disc and snubber arms connected to the body portion. The snubber arms extend from the body portion towards the disc and above and below the elevation of the disc, with each snubber arm having a distal end located at a position adjacent the disc between the inner and the outer radii of the disc and towards the outer radius of the disc. The height of each snubber arm limits deflection of the disc at the outer radius of the disc as a result of mechanical shock forced supplied to the disc drive assembly.

Abstract: In a medium having data fields and servo fields, a dual servo format includes a plurality of large and small servo fields for determining the position of a transducer over the medium. The large servo fields have a circumferential length that is larger than the circumferential length of the small servo fields. Both types of servo fields are distributed across the medium among the data fields.

Abstract: A pulse qualification apparatus and method provides for qualifying signal pulses from a raw data signal by comparison to a variable qualification level. Pulse qualification is done on a read signal developed by moving a magnetic transducer relative to addressable portions of a magnetic disk. A qualification level generator circuit generates a qualification level signal which varies in value depending upon the addressed portion of the magnetic disk. A threshold detector is used in qualifying pulses from a transducer read signal by comparison to the qualification level signal to generate an encoded pulse signal representing occurrences of qualifying pulses.

Abstract: A hard disk drive having a plurality of disks mounted on the rotor of a current limited, electronically commutated dc motor. Windings on the stator of the motor are divided into serially connected run and start sections and first and seconds drive circuits are provided to operate the motor by alternatively enabling the first drive circuit to pass currents serially through the two sections of the winding and enabling the second drive circuit to pass currents through only the run sections of the windings. During spin up of the disk drive to operating speed, the first drive circuit is enabled and the second drive circuit is disabled to drive the disks to the speed at which the back emf limits on the acceleration of the motor using both sections of the windings reduces the acceleration to the maximum acceleration achievable at the current limit using the run sections alone. Spin up is then completed by enabling the second drive circuit and disabling the first drive circuit.

Abstract: A method for optimizing settle characteristics of a read/write head on a data track on a rotating disk of a hard disk drive following a seek to the data track wherein each data track is assigned to a selected on of a plurality of concentric zones defined on the surface of the disk. Seeks are performed by a servo system in relation to a compensated velocity demand profile that provides velocities the head is to have at selected distances from a destination track and is selected for each zone by adding a velocity increment specific to the zone to a stored velocity demand profile for movement of the head in one direction and subtracted from the stored velocity demand profile for movement in the opposite direction.

Abstract: A prewrite compensation circuit for selectively delaying the writing of non-zero bits of data streams to disks of a hard disk drive. The hard disk drive includes a write circuit for writing the non-zero bits to selected portions of selected disk surfaces and selected write delays are effected by a variable delay circuit that receives the data stream from a shift register through which the data stream is passed. The amount of delay is determined by a delay word entered into a latch connected between the variable delay circuit and a RAM in which delay words are stored at addresses selected for each delay word in relation to the pattern of bits of the data stream surrounding each non-zero bit, the disk surface to which each data stream is to be written and the portion of the surface to receive the data stream.

Abstract: A pulse qualification apparatus and method provides for qualifying signal pulses from a raw data signal by comparison to a variable qualification level. Pulse qualification is done on a read signal developed by moving a magnetic transducer relative to addressable portions of a magnetic disk. A qualification level generator circuit generates a qualification level signal which varies in value depending upon the addressed portion of the magnetic disk. A threshold detector is used in qualifying pulses from a transducer read signal by comparision to the qualification level signal to generate an encoded pulse signal representing occurrences of qualifying pulses. Error recovery is accomplished by increasing or decreasing the qualification level of the address portion of the magnetic disk where the error occurs. This process is repeated until qualifcation channel requirements are met.

Abstract: A method for assigning tracks on a magnetic data storage disk to different zones in which data is written at selected zone frequencies so as to write data on the tracks at the maximum frequency that will limit the read/write error rate to a preselected value. A plurality of data bit groups is written onto selected tracks and read while checking for error to determine an error indication parameter for each of the zone frequencies. Tracks are assigned to frequency zones by determining such parameter for all tracks and assigning each track to the zone corresponding to the maximum frequency for which the error indication parameter is below the preselected value or by determining circular paths at which the error indication parameter has the preselected value for each of the selected frequencies and assigning all tracks between two consecutive circular paths to the lower of the two frequencies defining the circular paths.

Abstract: An adaptive prewrite compensation apparatus for writing data flux transition data on a magnetic medium, the apparatus incorporated in a disk drive assembly. A serial data pattern is introduced into the apparatus from a drive interface in digital form and is encoded. A combination of a transducing head and a writing location used for writing the data pattern on the magnetic medium is determined by the assembly. A predetermined write delay value based on the combination and the data pattern is computed by the assembly which then writes the data pattern on the magnetic medium with reference to the write delay value so that when the data pattern is read back, the flux transitions are preceived to be at the same distance as when entered into the apparatus.

Abstract: A microprocessor is used to measure the performance of a disk drive during each seek operation. By measuring track crossings per unit time of acceleration the deceleration of the servo arm can be delayed as long as possible to minimize unproductive access time. A performance ratio is calculated for each seek and the look-up table values of worst case performance are modified to fit measured actual performance values.

Abstract: A shock load detection device mounted on a disk drive housing of a computer disk drive unit to issue a write-fault signal should the disk drive unit have a mechanical shock imposed thereon. The detection device includes three piezo-electric crystals mounted orthogonally between a base and a seismic mass. Any shock load along x, y, and z axes through the piezo-electric crystals produces an electrical charge which is amplified, filtered, and compared for issuing a write-fault signal. The write-fault signal is used to stop the writing of read/write heads on a spindle of a head disk assembly before the shock imposed thereon could otherwise move the read/write heads off track causing a data error.

Abstract: This disclosure relates to apparatus and method for controlling and protecting an electric motor. A transmitter is coupled to the motor and to the power lines for generating pulses on the power lines in certain circumstances such as during an overheated motor condition. A control unit is coupled to the power lines and senses the pulses and monitors the power current magnitude in the lines. The unit compares the current level with previously established upper and lower limits. If the current level is outside the limits for a preset length of time, a fault condition exists and the motor is turned off for a length of time that depends upon the severity of the fault. The unit also turns off the motor upon the receipt of pulses from the transmitter when a certain number of pulses regularly recur. The unit includes indicators for displaying the nature of the fault.