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Detecting Head-To-Disk Contact in a Disk File

IP.com Disclosure Number: IPCOM000034038D
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-26
Document File: 2 page(s) / 129K

Publishing Venue

IBM

Related People

Annis, JW: AUTHOR [+2]

Abstract

Detecting head crashes in disk files during long-term testing is important. With the recent emphasis toward smaller files, past methods of detecting crashes, such as commercially available ultrasonic microphones and particle counters, are not feasible form both a technical feasibility and cost standpoint. The inherent features of piezoelectric polymer film suggest a better alternative to these past approaches. The advantages of using piezofilm crash-sensing are small (Image Omitted) size, high sensitivity, chemical inertness, and low cost. Because a the piezofilm polymer material is typically very thin and flexible, it can be easily fabricated into a geometry suitable for detecting the mechanical vibrations that occur during a head crash.

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Detecting Head-To-Disk Contact in a Disk File

Detecting head crashes in disk files during long-term testing is important. With the recent emphasis toward smaller files, past methods of detecting crashes, such as commercially available ultrasonic microphones and particle counters, are not feasible form both a technical feasibility and cost standpoint. The inherent features of piezoelectric polymer film suggest a better alternative to these past approaches. The advantages of using piezofilm crash-sensing are small

(Image Omitted)

size, high sensitivity, chemical inertness, and low cost. Because a the piezofilm polymer material is typically very thin and flexible, it can be easily fabricated into a geometry suitable for detecting the mechanical vibrations that occur during a head crash. A piezoelectric polymer material can convert an applied mechanical stress into an electrical charge. This is basically the definition of piezoelectricity. During a head crash, there is a considerable amount of energy dissipated in the form of mechanical vibration of the head and disk. Some of the energy manifests itself as head and disk vibration which is transmitted throughout a disk file through the structural elements as well as through the air inside the file. Bonding a piece of piezopolymer film to a vibrating member will cause the film to produce an output signal proportional to the vibration. For the highest sensitivity, the film should be placed close to the source of the vibrational energy. Directly attaching the piezopolymer to a head or disk is impractical and may actually interfere with the file operation. A pr...