Matsushita Electric Industrial Co., Ltd., best known for its Panasonic brand of consumer electronic and digital communications products, today announced that it has developed an innovative rewriteable dual-layer optical disc technology that uses a blue laser, a world's first.
In addition, Matsushita announced development of an advanced 50 GB optical disc that fully utilizes this new technology. Bridging the cutting edges of both IT and AV technologies, these new developments make possible interchangeable and large-capacity storage media with superior searching and operating capabilities. These developments will be presented at ISOM2001, the International Symposium on Optical Memory, in Taipei, Taiwan on October 19.
Recent years have seen great advances in optical disc technologies. Single-layer 120 mm phase-change discs, such as 4.7 GB (single-sided) and 9.4 GB (double-sided) DVD-RAM discs, have already been commercialized. Successful feasibility tests on dual-layer discs have similarly been carried out using red lasers. But until these newly announced developments by Matsushita, using a blue laser effectively for dual-layer optical disc operations has not been deemed possible.
The new optical disc achieves an industry-high 50 GB rewrite capacity on one side of a CD-size dual-layer disc by employing an ultra-thin recording layer for the half-transparent first recording layer (achieving more than 50% transmittance with a 6 nm recording film thickness) and superior recording and playback characteristics on the second recording layer. This represents a capacity more than 10 times larger than conventional rewriteable optical discs. The new technology also realizes a remarkable maximum recording and playback data transfer rate of 33 Mbps, 3 times faster than conventional DVD technology. These features make it possible to record more than 4 hours of digital high-definition moving pictures at a data transfer rate of 25 Mbps. Moreover, accurate recording/reading is ensured by using a transmittance-balanced structure to suppress interlayer interference.
The new disc technology features both a highly reliable GeSbTe (germanium antimony tellurium) film with excellent overwrite cyclability (greater than 10,000 cycles), and high sensitivity by writing with a 10 mW blue laser light spot that matches the power level of conventional optical disc technology. Along with a newly developed highly sensitive disc structure that creates a slight misalignment of the center holes between the first and second media, both layers can now be easily accessed from one side of the disc with highly stable tracking control.
Matsushita intends to apply these new technologies in the production of optical disc recorders for digital high definition video recording.