Browse Prior Art Database

New Pre-Formatting for Magneto-Optical Disk Mastering

IP.com Disclosure Number: IPCOM000120650D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Kobayashi, K: AUTHOR [+2]

Abstract

Disclosed is a new format giving an equivalent Tracking Error Signal (TES) to the conventional continuous tracking servo of Magneto-Optical (MO) disk.

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New Pre-Formatting for Magneto-Optical Disk Mastering

      Disclosed is a new format giving an equivalent Tracking
Error Signal (TES) to the  conventional continuous tracking servo of
Magneto-Optical (MO) disk.

      The present invention claims that sector header areas are
pre-formatted with embossed pits only, while MO data areas are
processed with pre-grooves only, as shown in the figure.  The
pre-grooves should be shallower than 0.25 lambda, and the embossed
pits should be deeper than 0.25 lambda, where lambda is the
wavelength of the read-out laser beam.  This depth is required
because the polarity of TES should be the same at track center, where
read-out spot is located in sector header area or MO data area.

      The geometrical shape and depth of the pre-grooves and embossed
pits, especially, depth, should be optimized so as to keep slope and
peak-to-peak amplitude of TES constant in any area, as much as
possible. At the same time, this optimization should be done so as to
have enough level of signals from the embossed pits. An example of
preferable depth, is 0.2 lambda to pre-groove, and 0.3 lambda to
embossed pits.

      This invention has the following advantages: it is easier to
control the process to give optimal structure of pre-grooves and
embossed pits because of no interference between grooves and pits.