Browse Prior Art Database

Sector And Index Pulse Generator

IP.com Disclosure Number: IPCOM000097668D
Original Publication Date: 1961-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Carothers, JD: AUTHOR

Abstract

Around the outer edge of a rotating disk D, several apertures a1... a9 are located as well as an elongated index aperture a10. Two photocells PC1 and PC2 are positioned to monitor the aperture path. D is fixed on a shaft S together with a number of magnetic recording disks (not shown). The disks have concentric circular tracks T divided into the separate sectors S.

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Sector And Index Pulse Generator

Around the outer edge of a rotating disk D, several apertures a1... a9 are located as well as an elongated index aperture a10. Two photocells PC1 and PC2 are positioned to monitor the aperture path. D is fixed on a shaft S together with a number of magnetic recording disks (not shown). The disks have concentric circular tracks T divided into the separate sectors S.

An indication of the start of a sector S0... S9 is represented by the leading edge of a pulse generated as each aperture passes PC2. By making aperture a10 sufficiently long, PC2 comes on before PC1 goes off. This simultaneous occurrence of PC1 and PC2 outputs (x) identifies an index or home location on D.

Any sector can then be detected by counting the PC2 pulses starting with the index pulse. The method is applicable to moving tape. Similarly, magnetic portions could be substituted for the apertures and detected by appropriate magnetic heads.

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