Western Digital Technologies, Inc.

Sperry Rand Corporation

Sperry Corporation

Information Storage Systems, Inc.

John Cuda

Mohamad Towfik Krounbi

Robert L Cloke

Jack M Chue

David Price Turner

Frank J Sordello

Gary L Dunbar

James Joseph Touchton

Patrick S Lee

Siu Kee Lee

A preamplifier circuit is disclosed comprising a data input for receiving write data, a read signal output for outputting an amplified read signal, a read signal input for receiving a read signal from a read element, and a write signal output for supplying a write signal to a write element. The preamplifier circuit further comprises a first amplifier circuit, responsive to the write data, for generating the write signal supplied to the write element, and a second amplifier circuit for amplifying the read signal from the read element to generate the amplified read signal output via the read signal output. A head control circuit, responsive to head select data, simultaneously enables the first and second amplifier circuits to perform a simultaneous read and write operation.

Preamplifier circuit configurable to allow simultaneous read and write operations for self-servo writing a disk drive

The present invention may be regarded as a self-servo writing disk drive comprising a head having a read element radially offset from a write element. During a first time interval, the read element is positioned over a first radial location to read first A clock data to generate first circumferential timing information and first A servo bursts to generate first position control information. The first position control information is used for positioning the write element over a second radial location, and the first circumferential timing information is used for writing second B clock data and second B servo bursts to the second radial location. During a second time interval, the read element is positioned over the first radial location to read first B clock data to generate second circumferential timing information and first B servo bursts to generate second position control information. The second position control information is used for positioning the write element over the second radial location, and the second circumferential timing information is used for writing second A clock data and second A servo bursts to the second radial location.

Self-servo writing a disk drive by propagating interleaved sets of timing clocks and servo bursts during alternate time intervals

A tachometer for generating a velocity signal in a data disc pack servo system comprising a sampling pulse generator for producing pulses that are spaced from one another by a constant amount representative of a distance increment of radial movement of a servo head in the system, a timer for measuring the time between the sampling pulses, the timer including a clock pulse source and a counter which is started by one sampling pulse and reset by the next succeeding sampling pulse so that the digital output thereof is proportional to time and a computer for computing average velocity by deriving the quotient of the distance increment divided by the time required for the servo head to traverse such distance increment.

Tachometer for deriving average velocity output by sampling position

A signal compensator for a position servo loop system to attenuate the position error signal and provide stability at a larger band width by limiting the position actuator current in selected frequency ranges.

Servo system with feedback signal compensation

A closed loop servo system for positioning a head relative to a magnetic recording element wherein track crossings are normally utilized to generate a feedback signal to the servo for positioning the head and wherein for a precise indication of head positioning between track crossings the velocity of movement of the head is integrated and fed into the servo system to provide a fine position signal.

Coarse and fine control for position servo

A circuit for controlling the gain of a transducer circuit by detecting the peak voltage of the transducer circuit, comparing the voltage with the reference voltage and modifying the output of the transducer circuit in a direction to adjust the output voltage towards a desired voltage.

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Saratoga, CA, United States of America

John Cuda