Carrier erasure current method for in-situ monitoring of head-disk spacing variation

Certain head/slider movements, such as seeking and dynamic load/unload, may lead to head-disk contact/impact. Such head-disk contact/impact is playing more and more important role in the disk drive failure. As a result, new methodology for the in situ monitoring of the head-disk interaction and the head-disk spacing change caused by such operations is becoming of crucial importance to the disk drive design and manufacturing. By applying a properly selected DC carrier erasure current on the writing head, the spacing variation during such operations can be recorded and tested. The carrier current is selected in such a way that the spacing change will result in a proportional modulation of the head field acting on the media and lead to a proportional modulation of the magnetization difference between adjacent bit cells. The theoretical background of the method, its working principles and major advantages are discussed. The method is of a unique advantage of getting spacing change recorded. The method is also of the advantage of high sensitivity to the variation of head-disk spacing comparing with other methods reported with read/write head as transducer.