| Popis: |
We have investigated the possibility of a direct overwritable MO disk system which uses light intensity modulation and a triple-layered disk of 130 mm to provide 1.3 GByte of capacity using both sides. The writing and reading performance was experimentally evaluated using an overwritable disk with 1.4 micrometers track pitch and 0.8 micrometers /bit linear density to give a 1.4 times increase in recording density. This recording format is the same as the ISO standard [(2,7)-RLL Code, mark position recording], so that we can maintain compatibility with the current MO disk systems. We also introduce a laser power off-time period after each recording mark in order to reduce thermal interference. The laser power margin is improved by this method from about +/- 17% to over +/- 30%. We confirmed that this is a sufficient margin for a practical system. We demonstrated the feasibility of a 1.3 GByte direct overwritable MO disk system by combining the higher recording density, the introduction of a laser off-time period, and zone bit recording techniques. |
