Browse Prior Art Database

Dual Media Optical Disk

IP.com Disclosure Number: IPCOM000114188D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Baca, FA: AUTHOR [+4]

Abstract

Ablative Write-Once Read-Many (WORM) optical media may not keep pace with the technology improvements seen in the rewritable Magneto-Optical (MO) media. Hence, there may be a desire to make MO media behave in an irreversible manner.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Dual Media Optical Disk

      Ablative Write-Once Read-Many (WORM) optical media may not keep
pace with the technology improvements seen in the rewritable
Magneto-Optical (MO) media.  Hence, there may be a desire to make MO
media behave in an irreversible manner.

      It is desired to have an irreversible label, one which would
say that the MO optical media is now considered WORM.  This label is
internal to each side or volume of the optical disk, so that it does
not affect any of the gross mechanical properties of the disk, such
as its mass, mass moment of inertia, thickness, and balance.

      A dual-media optical disk could be manufactured in a multi-step
process.  There would be a large MO zone and a small ablative WORM
zone.  The WORM zone could be close to the PEP (Phase Encoded Part)
label.  The MO portion of the disk could also be rewritable
phase-change media.
  1.  Mask off the WORM zone.
  2.  Deposit the MO media (large concentric area)
  3.  Remove the mask over the WORM media.
  4.  Mask over the freshly laid MO media.
  5.  Deposit the WORM media (small concentric area)
  6.  Remove the mask over the MO media.

      This allows the optical drive to check the WORM region just
after reading the PEP label.  Sector XY of track Z in the WORM region
would hold the binary "key" as to whether the disk was MO or WORM.
If Sector XY in Track Z of the WORM region is unwritten, then the
disk is an MO disk and it can be erased with impunity.  However, if a
special password is written in the binary "key" sector, then the MO
media cannot be considered erasable and is considered as WORM by the
drive.  It is preferred that this "key" is the Error Correction Code
(ECC) and Cyclical Redundancy Check (CRC) bytes of files written on
the optical volume...