Browse Prior Art Database

Disk Head Load/Unload Mechanism

IP.com Disclosure Number: IPCOM000040736D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Hatchett, MR: AUTHOR [+2]

Abstract

During operation each head is biased towards a disk surface by its arm and flies close to the surface. During starting and stopping, each head is moved away from its respective disk surface by one finger on a pair of comb structures which move differentially when driven by a shape memory alloy (SMA) spring opposed by a conventional coil spring. When the SMA spring is cold, each pair of fingers associated with a single disk move apart to unload the heads. When the SMA spring is hot, each pair of fingers move together to load the heads. Recent developments in disk file technology have made it necessary to unload the read/write heads during starting and stopping. This is due to the use of thin film disks which creates a stiction/friction problem between the ultra-smooth disk and head.

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Disk Head Load/Unload Mechanism

During operation each head is biased towards a disk surface by its arm and flies close to the surface. During starting and stopping, each head is moved away from its respective disk surface by one finger on a pair of comb structures which move differentially when driven by a shape memory alloy (SMA) spring opposed by a conventional coil spring. When the SMA spring is cold, each pair of fingers associated with a single disk move apart to unload the heads. When the SMA spring is hot, each pair of fingers move together to load the heads. Recent developments in disk file technology have made it necessary to unload the read/write heads during starting and stopping. This is due to the use of thin film disks which creates a stiction/friction problem between the ultra-smooth disk and head. Present head unload schemes are cumbersome and expensive and likely to cause contamination due to the use of cams and followers, etc. The mechanism disclosed uses a special material called Shape Memory Alloy (SMA) to provide the driving force. The material has the property that it can be changed regularly from a Martensitic phase to an Austenitic phase at a specific temperature within a wide range. The temperature is chosen by the properties of nickel and titanium used in the alloying. In the cold Martensitic phase, the material has a rhomboidal structure resulting in a relatively low modulus. When heated past the transition temperature, the material transforms to an Austenitic phase resulting in a high modulus face centered cubic structure. The ratio of modulus in these two phases is 3:1. If the material is kept within a reasonable strain (.01), it will allow gross distortions in the M...