Browse Prior Art Database

Digital Speed Control Drive Tilt Calibration Method

IP.com Disclosure Number: IPCOM000119661D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 82K

Publishing Venue

IBM

Related People

Kagami, N: AUTHOR [+3]

Abstract

Disclosed is a method for an optical disk drive to position the optical pickup under the grooved area of an optical disk in order to calibrate Focusing Error Signal (FES) and Tracking Error Signal (TES) electrically. The method is widely applicable to all linear Voice Coil Motor (VCM) actuator pickup systems. The method allows any drive orientation and tilted condition without special sensor which shows the physical position of the linear VCM actuator pickup.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Digital Speed Control Drive Tilt Calibration Method

      Disclosed is a method for an optical disk drive to
position the optical pickup under the grooved area of an optical disk
in order to calibrate Focusing Error Signal (FES) and Tracking Error
Signal (TES) electrically.  The method is widely applicable to all
linear Voice Coil Motor (VCM) actuator pickup systems.  The method
allows any drive orientation and tilted condition without special
sensor which shows the physical position of the linear VCM actuator
pickup.

      The method will be best understood with reference to the
drawing which schematically shows a servo signal calibration system.
Generally an optical pickup 5 should be under the grooved area of an
optical disk 6 when FES and TES are calibrated electrically.  FES
calibration means FES signal offset correction by FES correction
block 1, and TES calibration means TES signal offset and gain
correction by TES correction block 2.  These two correction blocks
are controlled by microprocessor 3 with sampling TES signal positive
and negative peak level using analog-to-digital converter 4.  An
optical pickup 5 is on a linear VCM actuator 7 and a linear VCM
actuator 7 is driven by VCM driver 8.  A track count signal generator
9 generates one pulse corresponding to track crossing of the laser
spot on an optical disk and that output pulse decrements a track
counter 10 contents.  During FES/TES calibration, microprocessor 3
can read the track counter 10 contents and control a VCM driver 8
output current or voltage using digital- to-analog converter 11.
General linear VCM actuator 7 control method is using actuator
positioning sensor 12 (shown in dotted lines in the drawing).

      In accordance with this method, FES and TES signal calibration
can be done without actuator positioning sensor 12 by linear VCM
actuator constant speed digital control. First of all, a
microprocessor 3 sets the digital-to-analog converter value which is
enough to push the linear VCM...