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Hard Disk Actuator Control under Power Save Mode

IP.com Disclosure Number: IPCOM000109201D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Okada, K: AUTHOR [+3]

Abstract

Current popularity of battery-operated portable computers has drawn user's attention to the power consumption of all the devices inside. The hard disk drive is not an exception. Described herein is a technique for the hard disk drive to reduce power consumption while minimizing the performance impact to the user.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 59% of the total text.

Hard Disk Actuator Control under Power Save Mode

       Current popularity of battery-operated portable computers
has drawn user's attention to the power consumption of all the
devices inside.  The hard disk drive is not an exception.  Described
herein is a technique for the hard disk drive to reduce power
consumption while minimizing the performance impact to the user.

      The technique described here can be easily applied to all MPU
(Micro Processor Unit) controlled servo systems.

      The read/write head is positioned by
1. Reading back the servo signal on the disk,
2. Calculate offset from the target position, and
3. Compensates by feeding back through the actuator motor if
necessary.

      This precise positioning is required during read/write data
process.  Some energy is consumed to position the head, which are
1. VCM current to position the head on the target,
2. Electric circuitry to read back the position signals, and
3. Control logic (MPU and its memory)

      This technique is to eliminate this tightly controlled cycles
when the disk medium are not accessed.  A disk drive is idle most of
time in the actual application.

      The most direct and simple way to achieve this is to cut off
all servo control.  The disadvantage of this is:
1. A head can freely move, and it may hit the crash stop to damage
a disk, and
2. Re-locking to the servo is required when the user makes a medium
access request.  This takes some extra time, wh...