Browse Prior Art Database

Disk File Variable Access Speed Method

IP.com Disclosure Number: IPCOM000052974D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Quinlan, WP: AUTHOR [+2]

Abstract

In a disk access mechanism wherein the torque required for moving read/write head from track to track of a concentric track media varies with the track number, access time can be optimized using such characteristic.

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Disk File Variable Access Speed Method

In a disk access mechanism wherein the torque required for moving read/write head from track to track of a concentric track media varies with the track number, access time can be optimized using such characteristic.

Where the linkage used in the access mechanism to move the read/ write head to a particular track requires torque in both directions to move to any track throughout the range of track locations, a spring is added to shift the torque curve such that torque is always applied in a single direction. This is illustrated in Fig. 1, where curve A shows the normal torque configuration wherein half the track positions require negative torque and the remainder require positive torque. Imposing a spring in the system displaces the torque curve to the position of curve B wherein positive torque is required for accessing each of the tracks. This causes the stepper motor that drives the access mechanism to encounter a torque that increases from track 0 to track N.

This variable required torque is used with the stepper motor characteristics to provide a machine with more efficiency and higher access speed. Typically, a stepper motor which drives the access mechanism has greater torque at lower angular velocities (or step rates), as illustrated in Fig. 2. Thus, when more torque is required for accessing, the drive can access at a slower step rate. Where control of the file is exercised by a microprocessor, variable step rates ma...