Browse Prior Art Database

Recovery Method from Unlock Condition

IP.com Disclosure Number: IPCOM000118588D
Original Publication Date: 1997-Apr-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Ozawa, Y: AUTHOR [+3]

Abstract

Disclosed is a method to eliminate bad effects due to a servo unlock condition during a seeking or track following state for a Hard Disk Drive (HDD) which has read and write heads and disks and a Load/Unload function with RAMP.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Recovery Method from Unlock Condition

      Disclosed is a method to eliminate bad effects due to a servo
unlock condition during a seeking or track following state for a Hard
Disk Drive (HDD) which has read and write heads and disks and a
Load/Unload function with RAMP.

      During unlock condition, this algorithm can produce proper
Voice Coil Motor (VCM) current by predicting from a previous servo
condition such as servo positioning, head velocity, moving direction,
state of track follow or seeking, etc.  If this function is not
supported, unexpected head moving may cause a crash stop hitting, or
produce abnormal sounds, or landing on a RAMP with some uncontrolled
state and finally, a fatal unrecoverable data hard error.

      The higher area density and lower fly height, the more
important to solve this sort of physical contact issue between a head
and a disk.  In other words, possible bad factors need to be
eliminated as much as possible.

After unlock, the proper VCM current can be calculated in a manner as
shown in the flow chart.