Hybrid HD Disc Patent Sought
By Greg Tarr -- TWICE, 9/25/2006
Burbank, Calif. — In what some may see as the possible end to the high-definition disc format war, three Warner Brothers employees have filed for a patent application on a multi-layer hybrid disc technology that would store both HD DVD and Blu-ray Disc content on a single disc, according to a report in New Scientist Magazine.
The technology, called a “multi-layer dula optical disc,” would use a single multi-layer double-sided disc to store Blu-ray content on one layer, HD DVD content on a second layer, and additional content — possibly standard DVD or even CD format content — on a layer on the flip side of the disc.
Both the HD DVD and Blu-ray Disc formats use 405nm blue-laser technologies to read and write discs, but the formats place data at different depths. Blu-ray data is written at 0.1mm from the surface of a disc, while HD-DVD information is written at 0.6mm from the surface.
The new approach uses a semi-reflective film that will allow the laser pickup to read both high-capacity layers on one side of the disc, leaving the flip side of the disc available for additional content.
The downside to the technology is it would constrict the amount of space available to each format to a single layer each. The Blu-ray format provides 25GBs for a single layer, while HD DVD allows 15GBs on a single layer.
The patent application was filed by two Warner Brothers engineers and an attorney, but does not list Warner Brothers by name.
Toshiba recently announced a triple-layer hybrid DVD/HD DVD disc that had developed to place both standard DVD and HD DVD content on a single disc. (See story on p.53)
