Sony doubles CD memory to face DVD threat

Electronics Times, July 17, 2000

Sony is planning to licence double density CDs (DDCD) with 1.3Gbyte capacity for the PC drive market, writes EETimes' Yoshiko Hara.

The disks, which are applicable to CD-rom, CD-recordable and CD rewritable formats, offer double the capacity by modifying current CD formats, according to a Sony spokesman.

The modifications include narrowing the track pitch from 1.6 to 1.1 micro m and shortening minimum pit length from 0.833 to 0.623 micro m. The numerical aperture (NA) is raised by 0.05, giving the new disks 0.50NA for playback and 0.55NA for recording.

Smaller pits are subject to errors. To cope with this the current cross- interleave Reed-Solomon error-correction code (CIRC) will be modified. The depth parameter in the CIRC will change from four to seven and the address format will be expanded. Sony will include a copy control scheme to meet increasing demands for security.

The new disks can be produced with current CD technologies and production facilities. According to Sony, manufacturers will be able to upgrade current 650Mbyte drives to 1.3Gbyte capacity by using a laser pickup with a higher numerical aperture lens and by altering a system- on-chip device with an error correction block.

The development is part of Sony's strategy to thwart DVD recordable drives. Some analysts are sceptical as to whether Sony's strategy will work.

Hiroshi Motohashi, of market research company Trend Concept, said: "DVD- ram will take time to take off anyway [without DDCD]. Market penetration of the DDCD formats will be dependent on OEM prices. PC manufacturers may look on DDCD favourably but what's the merit for drive manufacturers?"