Browse Prior Art Database

Zoned retract current control

IP.com Disclosure Number: IPCOM000123264D
Original Publication Date: 1998-Aug-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Endo, T: AUTHOR [+2]

Abstract

1. General description This document describes the new method of controlling actuator speed when the Hard Disk Drive (HDD) power is shut down. Controlling the actuator movement at power-off is not possible due to no power, but with this method, it can be done to some extent. As a result of this, we can optimize the actuator speed at crash stop hit and this contributes better performance of Contact Start Stop and better reliability as a consequent. 2. Concept ID Crash stop hit speed at power-off retract varies with the start position of retract motion. Hit speed will be minimum if the motion starts from OD and maximum if the motion starts somewhere between ID and MD.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

Zoned retract current control

  1.  General description
      This document describes the new method of controlling
      actuator speed when the Hard Disk Drive (HDD) power is shut
      down.  Controlling the actuator movement at power-off is
      not possible due to no power, but with this method, it
      can be done to some extent.  As a result of this, we can
      optimize the actuator speed at crash stop hit and this
      contributes better performance of Contact Start Stop and
      better reliability as a consequent.
  2.  Concept
      ID Crash stop hit speed at power-off retract varies with
      the start position of retract motion.  Hit speed will be
      minimum if the motion starts from OD and maximum if the
      motion starts somewhere between ID and MD.  This is
      because the retract current is generated by back EMF
      (electomotive force) of spindle motor, and the voltage
      gets lower with longer retract time.  Now, the following
      new concept was developed to improve above situation in
      order to achieve optimum crash stop hit speed at any
      condition, that is, regardless of start position of
      retract motion(=Pr).
      a.  Divide disk surface into N zones, where Pr locates.
      b.  Preset optimum retract condition(current)
          corresponding to each zone.
      c.  Apply the "preset" con...