Quantum Corporation

Xerox Corporation

Shugart Associates, Inc.

Microtek Storage Corporation

Donald V Daniels

Joel N Harrison

David A Brown

Warren L Dalziel

Charles D Flanigan

Bruce R Peterson

Albert S Chou

Harold C Medley

Terence H West

Peter A Ronzani

John S Lee

James Johnston

Ray Y Yokoyama

A servo calibration method is disclosed for a disk drive including a rotating data storage disk journalled to a frame and having a multiplicity of concentric data tracks defined on a major surface thereof and an actuator structure under the control of a programmed servo control microprocessor in response to coarse position information fed back to the microprocessor by a position encoder, and to fine position information fed back to the microprocessor by a data transducer reading from servo information prerecordced on the major surface of the disk, the actuator structure for moving the data transducer to each selected one of the data tracks during track seeking operations and for maintaining the transducer aligned with the data track during track following data read and/or write operations. Carried out during initialization, the method includes the steps of: automatically seeking to a region of radially outermost tracks, reading fine position information recorded in the single sector of each of a plurality of outermost tracks, and recording the outer track fine position information in memory; automatically seeking to a region of radially innermost tracks, reading fine position information recorded in the single sector of each of a plurality of innermost tracks, and recording the inner track fine position information in memory; for each data track to which a seek is initially commanded, which track lies between the outermost track region and the innermost track region, calculating with the microprocessor means a track centerline correction value lying between the outer track fine position information and the inner track fine position information, and applying the track centerline correction value so calculated as an offset value to the rotary actuator to correct any discrepancy between nominal track centerline defined by the position encoder.

Data transducer position control system for rotating disk data storage

A higher performance, higher capacity, low cost fixed (Winchester) disk drive avoids the need of a servo surface and servo channel for head positioning by use of a mass balanced rotary actuator, a polyphase optical head position transducer coupled closely to the actuator and head position correction information sampled from the data surface by the data head.

Fixed disk drive

A data storage device includes a frame, a rotating data storage disk defining a multiplicity of concentric data tracks on the major surfaces thereof and at least one data transducer head in close proximity to a said disk surface. A bidirectionally moveable electromechanical mover includes a microstep providing stepping motor supported by the frame. The electromechanical mover is moveable between and stabilized at a position related to each data track. A head mounting structure moved by the mover moves the head across the multiplicity of concentric data tracks. A bidirectional mover driver connected to the mover moves the structure to any selected one of said concentric data tracks in accordance with externally supplied track position information and maintains the structure substantially within data track during read and/or write operations by reference to the frame. A data track stabilization means includes the stepping motor and stabilizes the structure within a range between the boundaries of each data track. A time sampled fine position closed loop servo is connected to the driver and includes a single, data masked servo sector on a data surface of said disk containing track centerline servo control data therein readable by said head, a sample and hold circuit connected to the head during passes over the servo sector for holding control data read therefrom, and a correction signal generator connected to the sample and hold circuit for generating an offset signal for application to said driver to promote and maintain track centerline alignment of the head during read and write operations.

A servo calibration method is disclosed for a disk drive including a rotating data storage disk journalled to a frame and having a multiplicity of concentric data tracks defined on a major surface thereof and an actuator structure under the control of a programmed servo control microprocessor in response to coarse position information fed back to the microprocessor by a position encoder, and to fine position information fed back to the microprocessor by a data transducer reading from servo information prerecorded on the major surface of the disk, the actuator structure for moving the data transducer to each selected one of the data tracks during track seeking operations and for maintaining the transducer aligned with the data track during track following data read and/or write operations. Carried out during initialization, the method includes the steps of: automatically seeking to a region of radially outermost tracks, reading fine position information recorded in the single sector of each of a plurality of outermost tracks, and recording the outer track fine position information in memory; automatically seeking to a region of radially innermost tracks, reading fine position information recorded in the single sector of each of a plurality of innermost tracks, and recording the inner track fine position information in memory; for each data track to which a seek is initially commanded, which track lies between the outermost track region and the innermost track region, calculating with the microprocessor means a track centerline correction value lying between the outer track fine position information and the inner track fine position information, and applying the track centerline correction value so calculated as an offset value to the rotary actuator to correct any discrepancy between nominal track centerline defined by the position encoder.

An improved apparatus and method is disclosed for controlling the position of one moveable member relative to another. In the disclosed preferred embodiment of a rotating disk memory system, the moving member is a head carriage structure and the other is a frame carrying a rotating data storage disk. From externally supplied position selectron information, and from internally determined polyphase position information, open loop position changing movements are determined and carried out in accordance with monitored incremental polyphase position information generated during the movement. When a destination location has been reached one or more servo systems close loop in order to maintain the moving member precisely at the newly commanded location. A rotor for moving the member is an aspect of the present invention.

A dual magnetic head assembly is provided with asymmetrical crosstalk shielding. One of the heads includes a pair of mu-metal washers sandwiching a copper washer, the stacked washers surrounding the portion of the head including the read-write gap. The washers are enclosed within a copper plated mu-metal cap having a central opening through which the gap-containing portion of the head projects for cooperation with a magnetic medium. The other head is unshielded.

Crosstalk shielding assembly for addition to one head of a dual magnetic

A bidirectional, pure torque generating electromechanical rotor mounted to a frame includes flux return top and base plates, a generally annular permanent magnet secured to one of the plates and a generally annular rotatable coil assembly placed between the permanent magnet and the other of the plates.

Pure torque, limited displacement transducer

Improvements in a system for controlling the position of a head carriage structure of a rotating disk data storage system are disclosed. The improvements include circuitry for generating a polyphase track boundary signal which compensates for drift, and which doubles or further increases the track density to increase storage capacity. A track centerline sensor circuit is greatly simplified by including the function thereof as microcode routines within a dedicated digital control processor. Error signals are measured periodically across the entire useful field of the disk, and they are constantly updated, so that improved compensation for drift, runout and offset of the disk relative to the data transducer is achieved. Track overshoot during track seeking movements of the transducer is accomodated, enabling reduced track average access time. Self contained diagnostic routines and a direct digital read out provide system status and error messages to operators and maintenance personnel, thereby facilitating maintenance and adjustment.

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Santa Cruz, CA, United States of America

Donald V Daniels