Browse Prior Art Database

Scanning Head Gap Characterization

IP.com Disclosure Number: IPCOM000073477D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Knight, RD: AUTHOR [+2]

Abstract

This device is directed toward instrumentation for measuring the gap length of a magnetic head. The magnetic head comprises two ferrite pole pieces 10 and 11 having a glass gap 14 therebetween. High impedance electrometers 12 and 13 are connected to one end of pole pieces 10 and 11, respectively. An electron beam 15 is scanned across the recording surface of the magnetic head. As the beam 15 scans the interface between the ferrite pole piece and the glass gap, the current through the appropriate electrometer changes due to the difference in resistivity, and hence impedance, of the two materials. Thus, the interface can be precisely determined as being that point which provides a current midway between the levels measured when the circuit path excludes and includes the high impedance gap.

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Scanning Head Gap Characterization

This device is directed toward instrumentation for measuring the gap length of a magnetic head. The magnetic head comprises two ferrite pole pieces 10 and 11 having a glass gap 14 therebetween. High impedance electrometers 12 and 13 are connected to one end of pole pieces 10 and 11, respectively. An electron beam 15 is scanned across the recording surface of the magnetic head. As the beam 15 scans the interface between the ferrite pole piece and the glass gap, the current through the appropriate electrometer changes due to the difference in resistivity, and hence impedance, of the two materials. Thus, the interface can be precisely determined as being that point which provides a current midway between the levels measured when the circuit path excludes and includes the high impedance gap. The accuracy of determining this point is limited by the beam diameter which is typically on the order of 1000 Angstroms.

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