Browse Prior Art Database

Track Access Method for Optical Disk Drive

IP.com Disclosure Number: IPCOM000104595D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Kagami, N: AUTHOR [+2]

Abstract

Disclosed is a method for controlling Voice Coil Motors (VCM) which drive an optical pickup head in the optical disk drive in order to obtain a reliable track counting at the start of the track access. The disclosed method is widely applicable to any optical disk drive which has two degree Voice Coil Motor (VCM) actuator systems: one is a fine actuator and the other is a coarse actuator.

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This is the abbreviated version, containing approximately 67% of the total text.

Track Access Method for Optical Disk Drive

      Disclosed is a method for controlling Voice Coil Motors (VCM)
which drive an optical pickup head in the optical disk drive in order
to obtain a reliable track counting at the start of the track access.
The disclosed method is widely applicable to any optical disk drive
which has two degree Voice Coil Motor (VCM) actuator systems: one is
a fine actuator and the other is a coarse actuator.

      The method will be best understood with reference to the
drawings which show fine/coarse actuator movements at the start of
the track access.  Fig. 1 shows a conventional process of switching
from the track following mode to the track access mode.  During track
access, the fine actuator 1 will be mechanically or electrically
fixed at the center of the optical path.  If the coarse actuator 2
has some offset positioning just before starting track access (see
Fig. 1), a fine actuator movement 3 in the opposite direction will
cause the track miscounting at the start of the track access (see
Fig. 1).  In order to eliminate these track miscounting, the
disclosed method keeps the fine actuator 1 in track following mode
while remaining the coarse actuator positioning offset.  The control
steps at the start of the track access are as follows:

1.  Set Track Counting Counter

2.  Output Coarse Actuator Control Current or Voltage in order to
    move the Coarse Actuator toward Track Access Direction

3.  Wait Timer (Enough time to...