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 Sony Looks to 40GB Phase-Change Disk Sony Corp is now defining the 5.25-inch Ultra Density Optical (UDO) standard for phase-change optical disks, offering 20 Gbytes of recording capacity per side, for a total of 40 Gbytes. The firm plans to complete standardization by spring, with productization in the second half of 2002.It is positioned as the successor to the 9.1-Gbyte (double-side capacity) 5.25-inch magneto-optical (MO) disk to be productized early this year and will use the same cartridge and disk external dimensions. Areal recording density was increased by application of some technologies originally developed for the DVR-blue specification, now being formulated jointly with Royal Philips Electronics. The drive will use a 405nm blue-violet laser diode and 0.85 numerical aperture (NA) object lens. The media will probably be a sandwiched structure, using disks with 0.1mm thick cover layers. The firm will prepare both a rewritable specification and an appendable disk specification using the phase-change film. The track pitch is 0.33micron (land-groove recording), providing slightly more leeway than the 0.30micron of DVR-blue. The minimum recording mark length is 0.13micron, the record encoding is (1, 7) run length limited (RLL), and the data transfer rate from 4 to 8 Mbytes/s. (January 2001 Issue, Nikkei Electronics Asia) |
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