Toshiba ups the ante with announcement of dual-layer HD DVD-R

Tokyo (Japan) - Boosting its case in favor of next-generation DVD production using existing factories and machinery, Toshiba has won the adoption of its 30 Gb dual-layer HD DVD-R specification by the DVD Forum.

Adoption of a dual-layer version of HD DVD-R was widely expected, and is seen as the next step toward Toshiba’s completion of a full complement of recordable options, enhancing its credibility in its ongoing format war with Blu-ray, the competing next-generation optical disc standard championed by Sony. Dual-layer technology was originally created by Philips - ironically, a member of the Blu-ray camp - and introduced by the DVD+RW alliance in 2003. Dual-layer discs are single-sided ; there are separate standards for double-sided DVD discs today, and separate standards for dual-layer + double-sided discs are probably forthcoming by both camps.

In a statement, Toshiba said the new standard will be added to the HD DVD 1.9 specification, in advance of the 2.0 specification, which the company promises to release before the end of the year. Toshiba also stated it plans to bring to market a full-scale HD DVD-R recorder by Spring 2006.

With dual-layer discs, two layers of reflective dye are separated by a non-reflecting spacing material. The lower reflecting organic dye layer - the one closest to the recording surface - is given a relatively low level of reflectivity, especially by contrast to the upper organic dye layer, which is closest to the disc’s reflecting metal backing. When the laser reads the disc, the two reflections create a feedback that is interpreted as a "double signal." The electronics inside the drive can take apart the components of this double-signal, separating the upper layer component from the lower. Toshiba stated that it is acting in cooperation with a leading organic dye manufacturer, though it did not name that company.

Like existing dual-layer DVD, Toshiba states, HD DVD-R dual-layer discs can be produced by bonding two 0.6 mm substrates back-to-back. "As a result," a Toshiba spokesperson told Tom’s Hardware Guide today, "disc manufacturers can use existing DVD-R manufacturing lines for mass production, minimizing their investment in disc production equipment."

Speculation has risen that Toshiba may push for a three-layer, 45 Gb recordable HD DVD format, although presumably, such a format would require thinner substrates and vastly improved bonding techniques, which would require at least somewhat more investment by supporting disc manufacturers.

The Blu-ray Disc Association has already brought forth a dual-layer recordable specification for a 50 Gb disc, though Blu-ray’s standard would reportedly require disc manufacturers to invest in entirely new manufacturing equipment.