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Browse Prior Art Database

Self Calibrating Disk Storage Apparatus

IP.com Disclosure Number: IPCOM000086840D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Griffiths, DE: AUTHOR [+2]

Abstract

When flexible record disks are used for extremely high-density recording, concentricity perturbations can cause data-read and data-write errors. As track density increases, the ability of a servo-controlled actuator to maintain a transducing head continuously over a low-energy signal record track in a faithful manner becomes increasingly difficult. The track following problem can be alleviated by sensing high-energy tracks which are disposed in juxtaposition to the signal record tracks, memorizing the concentricity perturbations of such high-energy track and then feed forwarding the sensed perturbations to the actuator control for faithfully controlling the head-to-track relationship.

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Self Calibrating Disk Storage Apparatus

When flexible record disks are used for extremely high-density recording, concentricity perturbations can cause data-read and data-write errors. As track density increases, the ability of a servo-controlled actuator to maintain a transducing head continuously over a low-energy signal record track in a faithful manner becomes increasingly difficult. The track following problem can be alleviated by sensing high-energy tracks which are disposed in juxtaposition to the signal record tracks, memorizing the concentricity perturbations of such high- energy track and then feed forwarding the sensed perturbations to the actuator control for faithfully controlling the head-to-track relationship.

A record storage disk rotates about an axis concentric with a tachometer which indicates angular position. A plurality of concentric servo tracks, servo 1, servo 2 and servo 3 are prerecorded on the disk. Upon receiving a command to record or read on the disk in the respective data areas, one of the servo tracks is first sensed for measuring the concentricity perturbations. This is achieved by the microcomputer matching the angular position with the radial position indicated from the radial tachometer as the actuator track follows the head on the servo track. The time samples are stored in a memory as new profile data. Then the head is moved to the desired signal record Crack (low energy) with the memorized profile data supplied from memory via the microcomputer as old profile data to the actuator. The actuator adjusts the head in accordance with old profile data, with angular position of the disk, to overcome the perturbations in concentricity.

For reading or writing data in data one area, servo 1 servo track is first used for calibration. For writing or recording in either data 2A or data 2B area, servo track 2 is first used for calibration. If the perturbations are not severe, then the profile of servo track 1 can be used throughout the radial-recording extent of the record storage disk. S...