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Contact Monitor Technique for Fly Height Testing of Recording Heads

IP.com Disclosure Number: IPCOM000039173D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Yeack, CE: AUTHOR

Abstract

This technique prevents damage to recording heads and disks by monitoring contacts. One technique for testing the flying height of magnetic recording heads as well as other heads is optical measurement of interference fringes between the slider surface and a quartz (or glass) disk. A problem with this technique is that contamination causes head/disk contacts not visible in the interference fringes. A way of automatically preventing damage to the disk or to the head is as follows: l) Mount a motion transducer (or an array of such transducers) onto the underside of the glass disk and bring electrical contacts off through a coaxial spinning connector, such as a mercury contact. 2) Use a preamplifier, if necessary, very near the disk assembly to minimize noise. 3) Monitor the signal from the transducer(s).

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Contact Monitor Technique for Fly Height Testing of Recording Heads

This technique prevents damage to recording heads and disks by monitoring contacts. One technique for testing the flying height of magnetic recording heads as well as other heads is optical measurement of interference fringes between the slider surface and a quartz (or glass) disk. A problem with this technique is that contamination causes head/disk contacts not visible in the interference fringes. A way of automatically preventing damage to the disk or to the head is as follows: l) Mount a motion transducer (or an array of such transducers) onto the underside of the glass disk and bring electrical contacts off through a coaxial spinning connector, such as a mercury contact. 2) Use a preamplifier, if necessary, very near the disk assembly to minimize noise. 3) Monitor the signal from the transducer(s). The con tact will be evident in any of several ways, since it is a sharp pulse which will have a large spread of frequency components. For instance: l. The resonances of the glass disk will be excited.

By envelope detection at any of these resonant

frequencies, the contact will be apparent as an

increase in envelope voltage.

2. Surface waves can be detected, as generated by the

contact. In the same manner, we can "envelope detect"

the surface waves, and the contact will be apparent as

a voltage increase. 4) Use a threshold detector to: (a) shut down the tester, (b) automatically unload the head, an...