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Acoustic Sensor for Head/Disk Assembly

IP.com Disclosure Number: IPCOM000035988D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Landrock, J: AUTHOR [+4]

Abstract

This article describes an acoustic sensor for detecting head/disk interference (HDI) at an early stage, i.e., before an actual head crash. Each head is sensed by a microphone, detecting discordant noise by comparison with a reference value. The reference value is obtained by taking the mean of all noise values in the manner of a majority logic.

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Acoustic Sensor for Head/Disk Assembly

This article describes an acoustic sensor for detecting head/disk interference (HDI) at an early stage, i.e., before an actual head crash. Each head is sensed by a microphone, detecting discordant noise by comparison with a reference value. The reference value is obtained by taking the mean of all noise values in the manner of a majority logic.

The described concept is based on the fact that slightly changed flight characteristics of the read/write heads constitute a latent danger that may lead to a head crash and that such marginal errors are best detected by testing the heads for wind noise. The acoustic signals of all heads of the disk pack are compared with each other, the advantage of this being that discordant noise is readily filtered out.

In disk memories, the write density is essentially determined by the spacing of the read/write heads from the disk surface. Small spacings require maximum precision during manufacture and elaborate quality checks. It has been found that a head crash occurs more frequently at smaller spacings, which proves that not only dust particles but also manufacturing tolerances contribute to crashes. It may generally be assumed that the system involved is a complex mechanical one, in which minor defects or errors, occurring during the manufacture or in response to deformation of the head suspension, caused by head stiction, may add up. Such marginal errors must be detected at an early stage, because a head crash does not only mean a total loss of the disk but also a loss of stored data.

The auxiliary means for disk storage...