Browse Prior Art Database

Early Detection of Spindle Speed

IP.com Disclosure Number: IPCOM000108567D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Goodman, BG: AUTHOR [+2]

Abstract

Detection of spindle motion can be detected more quickly to improve both spin-up and spin-down times for an optical disk drive by use of both the accurate index pulse and an additional less accurate but higher sampling rate pulse.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Early Detection of Spindle Speed

       Detection of spindle motion can be detected more quickly
to improve both spin-up and spin-down times for an optical disk drive
by use of both the accurate index pulse and an additional less
accurate but higher sampling rate pulse.

      The current method of determining spindle speed is to monitor
the once per revolution index pulse and by measuring the time between
index pulses, determine if the spindle is rotating and what its speed
is.  A similar method is used when spinning down the motor to detect
when the spindle has come to a complete stop so that the unload
sequence can begin.

      Fast and accurate speed detection is necessary in order to
minimize the load-to-ready and unload times.  This article proposes
the use of a higher sampling rate pulse, say, 12 times per
revolution, to be able to detect initial motion.  In some optical
disk applications, the laser cannot be powered on until sufficient
media velocity has been reached.  This occurs at a velocity lower
than the final velocity.  If sufficient motion can be detected
quickly by using a higher sampling rate, significant time can be
saved in bringing the drive to a ready condition.

      As the spindle slows down during a spin down and unload,
significant time can occur between index pulses in order to detect
that the motor has stopped or has at least arrived at a safe velocity
to begin the unload sequence.  If a higher sampling rate signal is
avai...