Matsushita Electric Industrial Co says it has developed technology capable of creating a CD-size rewritable optical disk that could store 15 gigabytes of data per side, according to the Nikkei Daily News. The technology, compatible with DVD-RAM and DVD-ROM media, employs a blue semiconductor laser to maximize recording density. With nearly six times the data capacity of a digital video disk, the disks could store seven hours of conventional video or two hours of high-definition video data, the company claims. Nikkei also reports that Sony Corp and Philips Electronics NV have begun work on the joint development of high-density optical disks for improved digital recording. They will employ a technology called direct stream digital for an advanced storage device with improved signal quality. Direct stream digital widens the dynamic range of digital signals to 120 decibels or more, compared with 98 decibels for compact discs, while offering a replay frequency band of 100-Khz, against 22-Khz for CDs, Sony says. The firms have already developed a prototype disk system for playback.
