19 Dec 2003
NEC unveils a DVD optical head that can record and play back both current- and next-generation DVDs.
NEC of Japan has developed a DVD optical head technology capable of recording and playing back both current- and next-generation DVDs. The optical head contains two laser diodes, a red device for playing and recording current-generation DVDs and a blue/violet device for the emerging HD (high definition, high density) DVD standard.
The use of single optical head that can play both types of DVD through a single objective lens will reduce the size of future DVD players compared with systems that require a separate optical head for each laser.
NEC and Toshiba have jointly proposed HD DVD as the next generation DVD format. The use of blue/violet lasers enhances the storage capacity compared with current DVD technology. Recently, the DVD Forum approved the proposed HD DVD read-only memory format.
One of the strengths of the HD DVD format, compared with the competing Blu-ray format, is the compatibility with current generation DVDs. NEC says that the development of the single optical head should enable a smooth transition from current DVDs to HD DVDs.
With the spread of high-resolution digital images, large-screen displays, and the start of terrestrial digital TV broadcasting, NEC anticipates a growing need for integration of high-resolution content into DVDs in the home and in PCs. As current DVD software has spread rapidly the need for compatibility with current DVDs is an important consideration.
As well as developing a single optical head, NEC has also made other technology advancements including the development of suitable integrated circuits to cope with the dual-format capability, and the development of playback signal processing technology.
The HD DVD read-only memory disc has a storage capacity of 15 GB on a single layer and 30 GB on dual layers. A rewritable format with a capacity of 20 GB has also been proposed.
HD DVD discs are the same size as current DVDs, and do not require a cartridge, making it possible to realize thin drives suitable for mounting on notebook PCs, for example. The physical similarity will also allow disc makers to continue to use the same manufacturing infrastructure.
NEC expects that the optical head technology will significantly improve the prospects for HD DVD, and plans to make further technological improvements to promote product development.