Warner Files for Hybrid HD Disc Patent

In December 2005, three optical disc engineers now identified as working for Warner Bros. began work on a U.S. patent application for a three-layer optical disc, which would be capable of being adapted to any of 22 different configurations. One enables a hybrid DVD / HD DVD or DVD / Blu-ray configuration, and another would allow for a hybrid HD DVD / Blu-ray disc.

The patent application, dated August 10, 2006, may have used the strongest language put forth by a representative of a major studio against the notion that either format would ever win the high-definition format war.

"A general problem with multiple formats of discs," states the application, "is that disc manufacturers must make various types of discs of each type in order to satisfy consumer demand for the content on those discs. A consumer that owns a standard DVD disc player can only play DVDs with a standard format. A consumer with a Blu ray recorder can only play Blu-ray format recordable discs. And a consumer with an HD-DVD disc player can only play HD-DVD discs or standard format DVDs, but not Blu-ray format discs.

"From the standpoint of a manufacturer," the application continues, "it is disadvantageous to have to manufacture and distribute three different types of disc formats to satisfy consumer demand for one product - such as a motion picture. Moreover, multiple formats of DVD discs create retail and consumer confusion as to which format(s) to acquire or buy."

If these engineers truly speak for their company -- as they are legally obliged to do with regard to a patent of this nature -- then it's no wonder that Warner made the decision in October 2005 to support not just HD DVD but Blu-ray as well.

The basic theory put forth by the patent application is that a hybrid disc could be assembled in a wide variety of ways, in which as many as three layers are stacked atop one another, with their reflective surfaces protected inside. Once a hybrid disc player is able to determine the assembly of the disc, it can adjust the lenses as necessary to guide the red or blue-indigo laser beam to point to the appropriate depth.

The application appears to make the case that the layers themselves can be used to minimize attenuation of the beam as it makes its way to the appropriate reflective layer. Layers don't need to be 100% reflective to be effective - a dual-layer BD disc, it says, can be as low as 12% reflective and still be adequate.

The degree to which any layer is not reflective is precisely the amount that it enables light to pass through - what optics calls transmissivity. With the proper arrangements, the application says, the transmissive properties of layers designed for multi-layer discs can be exploited to the hybrid disc's advantage.

One problem, which the application briefly touched upon, may be that some configurations of Warner's hybrid disc might only be applicable to hybrid disc players capable of adjusting their lenses to the proscribed depths. But if such a player were standardized, it could enable studios to produce a single type of disc for both current and next-generation content.

The hybrid disc itself could be the norm, it states; even a disc designed for high-def content only could contain "boilerplate" messages on the DVD layer, instructing the user that this disc can't be viewed with standard DVD players.

While the application was recently discovered in the U.S. Patent and Trademark Office database, it has not yet been granted, and may not be granted for some time even if it's put on "fast-track" status. The biggest hurdle facing Warner engineers now may be from Toshiba, which appears to be ready to actually produce a three-layer hybrid disc in a joint venture with Memory-Tech, but only for HD DVD and standard DVD content.