Toshiba Corporation has announced the development of a triple-layer HD DVD-ROM (read-only) disc with a data capacity of 45 gigabytes, 50% more than the 30-gigabyte dual-layer HD DVD-ROM disc already announced and enough to record twelve hours of high-definition movies on a single disc. The new disc adds a high-end option to the previous HD DVD-ROM disc lineup that includes the 15GB (single-layer, single-sided) and 30GB (dual-layer, single-sided). These two discs are already approved and standardized at the DVD Forum.
Toshiba also announced a double-sided, dual-layer hybrid ROM disc comprised of dual-layer HD DVD-ROM side and dual-layer DVD-ROM side. The hybrid disc can store 30GB of high-definition content on the HD DVD-ROM side and 8.5GB of standard-definition content on the DVD-ROM dual layer side. More than 84 million DVD players and recorders were produced worldwide in 2004 alone. The standard definition content of the new hybrid discs can be replayed on these platforms, while their owners will also be able to enjoy high-definition content from the same source when they purchase HD DVD players in the future. The new disc further prepares the way for a smooth transition from DVD to HD DVD.
Details of these new discs will be presented at the 11 May HD DVD workshop at Media-Tech Expo 2005 in Las Vegas, U.S., an annual trade show for the optical disc manufacturing industry.
All these new versions of HD DVD-ROM discs share the same disc structure as previously announced HD DVD formats, and today's DVD format: two 0.6-mm thick discs bonded back-to-back, a time-tested physical structure with proven volume manufacturing capability at little cost increment.
Memory-Tech Corporation, Japan's largest independent disc replicator, has confirmed the new 45GB and hybrid discs can be produced on their existing manufacturing lines and equipment, which are tailored to produce HD DVD discs, with only minor additional investment and minimum additional production cost per disc.
The newly developed ROM disc has a single-sided, triple-layer structure. Each layer stores 15 gigabytes of information. Triple-layer discs can be easily produced by back-to-back bonding of a 0.6mm-thick dual-layer disc and a single-layer 0.6mm disc.
In the process, a single-layer disc is first produced, using the same process as for HD DVD-ROM. Next, the second layer is formed on first layer using a one-time polycarbonate stamper, the same process used for the DVD-18 disc, the double-sided DVD disc that has dual-layers on both sides. Finally, the single-layer 0.6mm disc is bonded to the dual-layer disc, using standard technology.