Toshiba Corp. will develop its own DVD next-generation optical disc using a blue-violet laser light source. Toshiba isn't adopting the large-capacity optical disc video format "Blu-ray Disc" standard, which was settled jointly by nine leading AV equipment makers of Japan, Europe, and Korea in February 2002.
An executive of Toshiba Digital Media Network Company said, "Toshiba decided to adopt the new DVD recording/playing method (0.6mm method), which is composed of the optical system, with the numerical aperture (NA) around 0.65 objective lens and the disc of two 0.6mm thick disc substrates stuck together," which is easier to get compatibility with current DVDs.
For comparison, the Blu-ray Disc standard adopts the "0.1mm cover layer method," of which the disc cover layer is 0.1mm thick and its DVD system is combined with a total 1.2mm thick disc and objective lens of NA 0.85.
Toshiba expects the merits of its "0.6mm method," which has the same disc construction as that of the current DVDs, to be as follows:
1) The recording media of its method can be easily manufactured by diverting the current DVD disc manufacturing facilities, along with the easiness of obtaining the compatibility with the current DVDs;
2) It is easy to spread the Working Distance, the distance between a disc surface and an objective lens; and
3) There is no need for a cartridge housing the disc.
On the other hand, it requires tilt-support and other features to suppress the generation of tilt-angle due to the disc's bend and tilt.
Aiming for 30GB on Double Layers
Toshiba expects the high capacity data recording of 18GB to 20GB on a single-sided single layer to play back only media and around 15GB on a rewritable media. It is estimated that Toshiba will apply the partial response maximum likelihood (PRML) signal detection process in order to attain the higher data recording capacity.
Regarding the recording capacity, while it is less than that of the Blu-ray Disc's around 25GB, Toshiba expects that 27GB to 30GB of data can be stuffed into a disc by applying the recording media of single-sided double layers. "It can record around three hours, even BS digital broadcast moving pictures with a high encoding speed of around 20Mbps. Moreover, recently the encoding speed has become suppressed to as low as around 10Mbps, even for processing HDTV-grade moving pictures, due to significant progress of the data compression ratio, such as the MPEG-2 standard," a Toshiba officer said.
Toshiba has been in hot pursuit of the Blu-ray Disc camp, which has been going ahead settling the standard specifications, aiming to commercialize the appliances at around the same period of Blu-ray Disc camp firms. NEC Corp. is expected to approve the method. Toshiba expects to settle the method specifications during 2002 and launch volume manufacturing of the appliances during 2003 in an early case. It looks to be almost inevitable that the next-generation DVD standard will actually be split into a few methods.
The DVD Forum is going to promote the study of this 0.6mm method in one of its working groups. On June 4, the DVD Forum decided to establish two sub-groups for studying the 0.6mm method and the 0.1mm cover layer method, respectively, affiliated to the "WG (Working Group) 11," which studies next-generation optical disc technologies. Further more, a sub-group for studying the 0.1mm cover layer method continues to study the Blu-ray Disc standard as one candidate.