Velocity controlled disk drive head retraction with reduced...

Details Velocity controlled disk drive head retraction with reduced... Velocity controlled disk drive head retraction with reduced...

2006-05-09

2006-05-09

Wong, K. (Department: 2651)

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Controlling the head

Reexamination Certificate

active

07042672

ABSTRACT:
A control circuit controls current through a voice coil motor (VCM) during retraction of a transducing head from the surface of a recordable medium. The transducing head is carried on movable member actuated by the VCM. The control circuit includes a measuring circuit for measuring a back electromotive force (back EMF) from the VCM. The control circuit also includes a driver circuit connected to terminals of the VCM for providing the VCM with a drive current having a magnitude based on the back EMF from the VCM. The control circuit further includes a chop clock to alternate between measuring the back EMF from the VCM and providing the VCM with the drive current at a random frequency within a range of frequencies around a median frequency.

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