Disk drive comprising VCM stall detector for velocity...

Details Disk drive comprising VCM stall detector for velocity... Disk drive comprising VCM stall detector for velocity...

2005-03-15

2005-03-15

Hudspeth, David (Department: 2651)

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Controlling the head

C360S075000

Reexamination Certificate

active

06867944

ABSTRACT:
The present invention may be regarded as a disk drive comprising a disk, a head, an actuator arm for actuating the head radially over the disk, and a voice coil motor (VCM) for rotating the actuator arm about a pivot, the VCM comprising a coil comprising a VCM resistance R. A back EMF voltage detector measures a back EMF voltage across the coil, and a current detector detects a current I flowing through the coil. An IR voltage detector, responsive to the current I detected by the current detector, detects an IR voltage proportional to the current I times the VCM resistance R. A voltage compensator substantially cancels the IR voltage from the measured back EMF voltage to generate a compensated back EMF voltage. A control voltage generator, responsive the compensated back EMF voltage, generates a control voltage applied to the coil to generate the current I flowing through the coil. A stall detector compares the current I detected by the current detector to a threshold, wherein a VCM stall condition is detected if the current I exceeds the threshold for a predetermined interval.

REFERENCES:
patent: 5297024 (1994-03-01), Carobolante
patent: 5384524 (1995-01-01), Romano
patent: 5663846 (1997-09-01), Masuoka et al.
patent: 5781363 (1998-07-01), Rowan et al.
patent: 5982130 (1999-11-01), Male
patent: 6021015 (2000-02-01), Jeffrey et al.
patent: 6163430 (2000-12-01), Hansen

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