Browse Prior Art Database

Inductive Read Head

IP.com Disclosure Number: IPCOM000078565D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Bajorek, CH: AUTHOR [+2]

Abstract

An inductive magnetic reading head has been provided for reading magnetically stored data serially, or in a scanned mode.

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Inductive Read Head

An inductive magnetic reading head has been provided for reading magnetically stored data serially, or in a scanned mode.

As seen in the figure, the inductive head, in its simplest form, comprises a coil 2 wound about a soft magnetic material 4, such as permalloy, positioned vertically above a storage medium 6. The sensing head has a thickness t, a width W, a track width L and a flying height h above the medium.

When the head is used conventionally as a serial reader of tracks, the voltage induced in the coil by flux reversals in the permalloy head is directly proportional to the data rate (linear bit density X medium velocity) flow under the head. At data rates where f approx. 20Mhz, voltage signals are sufficiently high to be sensed with state of the art amplifiers.

Scanning of the sensing head can switch the magnetization of the soft magnetic material 4 at a much faster rate than the frequency of the data moving in storage medium 6 under it, so as to provide large signal voltages. Thus, if a sonic pulse L mils wide (or T seconds long) is made to propagate along the sensor in the direction of the arrow, such propagated pulse in coincidence with the field emanating from the storage medium will switch one or more portions of the sensor. The resulting voltage signal V(S) approx. delta phi over delta t approx. L phi(0) over T approx. 25 microvolts/ coil turn/100 angstroms sensor thickness, where L 10/8/T mils, phi(0) peak flux/mil of switch sens...