Browse Prior Art Database

Quick Opening of Disk Stack

IP.com Disclosure Number: IPCOM000088686D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

McGinnis, BW: AUTHOR [+3]

Abstract

It is known [1] that co-stacked/co-rotating/closely-confined flexible disks can be separated peripherally, without abrasive contact, for external transducing access on a random-access basis. Air supplied internally for centrifugal circulation between the unseparated disks is throttled below a deflection equilibrium. If the equilibrium of the unseparated stack is then disturbed at one interface position, the rotating disks "self-deflect", relative to that position, to a second equilibrium configuration, forming an opening wide enough (and positionally stable enough) to accommodate an externally transported transducer.

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Quick Opening of Disk Stack

It is known [1] that co-stacked/co-rotating/closely-confined flexible disks can be separated peripherally, without abrasive contact, for external transducing access on a random-access basis. Air supplied internally for centrifugal circulation between the unseparated disks is throttled below a deflection equilibrium. If the equilibrium of the unseparated stack is then disturbed at one interface position, the rotating disks "self-deflect", relative to that position, to a second equilibrium configuration, forming an opening wide enough (and positionally stable enough) to accommodate an externally transported transducer.

The timing of the self-deflection transition (opening time), which determines the access time to individual layers of the stack, can be as long as 1/2 second. This can be reduced to about 150 miliiseconds by (a) keeping the internal pressure above bistable before selection; (b) applying force peripherally at one layer position by an air nozzle (Fig. 1) which partially opens the stack at that position; and (c) when the partial opening is at the selected position, which is to be accessed, transiently throttling the internal pressure into the range for bistable operation, thereby causing the partial opening to widen to complete size opening by "self-deflection" of the disks (Fig. 2).

A further reduction to about 30 milliseconds can be achieved (Fig. 3) by inserting a 2-stage spreader blade (e.g., as described in [2]) in coord...