Browse Prior Art Database

Servo Concept With Multi-Element Transducers for Achieving High Track Densities

IP.com Disclosure Number: IPCOM000041481D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Albrecht, DW: AUTHOR

Abstract

Future objectives for data storage areal density in DASD (direct-access storage device) products will require track densities greater than 1600 tracks per inch. To accomplish this, it has been proposed to servo the actuator with one of two basic techniques: 1. Embed servo information either magnetically, optically, or capacitively beneath the disk magnetic recording layer used for data and read this servo information with a transducer located to the side of the read/write (R/W) transducer. These approaches add significant complexity to the disk process and some are functionally incompatible with specific technologies proposed for the magnetic recording layer. 2.

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Servo Concept With Multi-Element Transducers for Achieving High Track Densities

Future objectives for data storage areal density in DASD (direct-access storage device) products will require track densities greater than 1600 tracks per inch. To accomplish this, it has been proposed to servo the actuator with one of two basic techniques: 1. Embed servo information either magnetically, optically, or capacitively beneath the disk magnetic recording layer used for data and read this servo information with a transducer located to the side of the read/write (R/W) transducer. These approaches add significant complexity to the disk process and some are functionally incompatible with specific technologies proposed for the magnetic recording layer. 2. Record servo information in radial sectors at regularly spaced intervals around the disk and sample that information with the R/W transducer to control the radial position of the head. The number of sectors must be limited so as not to cause significant loss of surface area for recording data. This limits the sampling rate and leads to aliasing which can limit the achievable track density. Sector Servo also adversely affects the settling time for a seek, and places some limitations on the data channel and data formatting. This disclosure proposes that servo information be located in continuous circumferential bands, as indicated in Fig 1. If a multi-element servo transducer of N elements, as shown in Fig. 2, is placed alongside a single R/W transducer, the R/W transducer can cover (N-1) data tracks at the expense of one servo track. For example, consider the case where 8 servo elements with each element on a four track pitch is fabricated with the end servo element spaced away from the R/W transducer by some multiple of 4 tracks. That R/W transducer can cover a data band of 28 tracks using only a four-track-wide servo band by appropriately switching and selectin...