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Browse Prior Art Database

Write Wide Read Narrow Tunnel Erase Magnetic Head

IP.com Disclosure Number: IPCOM000077238D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Shelledy, FB: AUTHOR

Abstract

Degradation of magnetic head signals read from one track due to adjacent-track signals or unerased previously recorded data is prevented by making the read track width narrower than the written track, erasing strips between tracks (tunnel-erasing), or both.

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Write Wide Read Narrow Tunnel Erase Magnetic Head

Degradation of magnetic head signals read from one track due to adjacent- track signals or unerased previously recorded data is prevented by making the read track width narrower than the written track, erasing strips between tracks (tunnel-erasing), or both.

In Fig. 1, a single-turn vertical film head with a central section and two narrower adjacent sections, writes wide and reads narrow and also tunnel- erases. Four copper (or other highly conductive, nonmagnetic metal) leads, A, B, C, and D, are sandwiched between magnetic (i.e., Permalloy) yokes on a nonconductive or semiconductive substrate.

In Fig. 2, outside leads A and D are connected to a write driver, and the inside leads E and C to a sense amplifier. The written track has a width Wl + 2W2, but, during reading the sense amplifier sees only the signal from the central section having width W1. The impedance of the sense amplifier should be greater than that of the central section of the head by four or more times, so that the leakage current will not reduce the write current excessively. The spacing between yokes should be very narrow so that there will not be an undesirable region of magnetization. During the writing, the sense amplifier will be exposed to large signals which may be used to check whether writing has occurred.

In Fig. 3, the head is connected to operate as a tunnel-erase write head. If resistor R2 >> resistor R3, and if input voltage E is s...