Power off velocity control for disk drives

Details Power off velocity control for disk drives Power off velocity control for disk drives

1999-06-09

2000-10-31

Masih, Karen

Electricity: motive power systems

Motor-reversing

318368, 318632, 318364, 360 7804, 360 75, H02P 100

Patent

active

061407844

ABSTRACT:
A method and circuit for controlling a voice coil motor (VCM) for a disk drive actuator assembly such that the actuator assembly moves to a landing area at a constant velocity when the disk drive loses power. The circuit includes a sense amplifier for sensing and amplifying current to the VCM, a current integrator for determining the actual velocity of the actuator assembly during every seek, an H-bridge driver, which controls the direction of current to the VCM and magnitude of voltage across the VCM and a window compare and logic block that receives and sorts information from the integrator, and a timer. The window compare and logic block determines the direction of current and magnitude of voltage to apply to the VCM. During a loss of power, e.g. a power down or sudden loss of power, the actuator assembly is controlled through a sequence of movements, depending on the position and actual velocity of the actuator assembly/transducer head at the moment power was lost, to ensure that the transducer head is retracted to the landing area at a constant velocity.

REFERENCES:
patent: 5473230 (1995-12-01), Dunn et al.
patent: 5495156 (1996-02-01), Wilson et al.
patent: 5668679 (1997-09-01), Swearingen et al.
patent: 5737144 (1998-04-01), Ataee
patent: 5739994 (1998-04-01), Ottesen et al.
patent: 5872670 (1999-02-01), Ataee
patent: 5969899 (1999-10-01), Swearingen et al.

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