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Measurement Apparatus for Obtaining the Thermal Response of Magnetoresistive Heads for Magnetic Reading

IP.com Disclosure Number: IPCOM000083303D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Hempstead, RD: AUTHOR

Abstract

Magnetoresistive heads have thermally induced noise, due to frictional heating between dust particles or other asperities on the surface of the recording media as they are dragged across the head surface. Various schemes have been proposed to reduce the amplitude of the resulting thermal noise spikes, such as use of a silicon substrate and a sapphire cover chip on a head. When built, it is not possible to determine the precise reduction in thermal noise amplitude. because of random-noise spikes.

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Measurement Apparatus for Obtaining the Thermal Response of Magnetoresistive Heads for Magnetic Reading

Magnetoresistive heads have thermally induced noise, due to frictional heating between dust particles or other asperities on the surface of the recording media as they are dragged across the head surface. Various schemes have been proposed to reduce the amplitude of the resulting thermal noise spikes, such as use of a silicon substrate and a sapphire cover chip on a head. When built, it is not possible to determine the precise reduction in thermal noise amplitude. because of random-noise spikes.

This measurement apparatus measures the precise thermal response of a magnetoresistive head. For heads of the two-stripe differential noise cancellation type, this apparatus determines the exact nature of the noise spike cancellation. This measurement is important, because small misalignment in two-stripe heads causes poor thermal noise cancellation. This apparatus is useful in quality control of manufactured heads.

A diagram of the apparatus is shown. The beam B from a laser L is expanded by beam expander E to expanded beam EB, which is deflected by mirror M rotated by motor 4. Deflected beam DB is focused into beam FB by a lens 5, set at its focal length above head surface H. By controlling the speed of motor 4, the speed of the beam FB traversing head H is controlled and set to the head/media relative velocity, to simulate an actual frictional heat source.

An electri...