Philips Collaborates with Mitsubishi Kagaku Media/Verbatim to Develop Dual-layer DVD+R Technology
Posted Oct 7, 2003

Philips will demonstrate its new dual-layer DVD recordable technology at the DVD+RW Alliance booth at the CEATEC* JAPAN 2003 exhibition in Makuhari from October 7 to 11. Developed by Philips Research in cooperation with MKM, the technology doubles data storage capacity on DVD recordable discs from 4.7 gb to 8.5 gb, while remaining compatible with existing DVD Video players and DVD-ROM drives.

Both Philips' and MKM's introduction of dual-layer DVD+R technology is important in the drive to continually improve and expand the optical data storage options available to consumers. Users will benefit from the additional storage capacity of the DVD+R disc. It will enable them to record 4 hours of DVD-quality video, or 16 hours of VHS-quality video, without the need to turn over the disc.

The dual-layer DVD+R system uses two thin embedded organic dye films for data storage separated by a spacer layer. Heating with a focused laser beam irreversibly modifies the physical and chemical structure of each layer such that the modified areas have different optical properties to those of their unmodified surroundings. This causes a variation in reflectivity as the disc rotates to provide a read-out signal as with commercially pressed read-only discs.

Compatibility has been achieved through the use of a thin silver-alloy as reflector material in the upper layer giving a reflectivity from the layer of at least 18% in compliance with the dual-layer DVD-ROM standard. In addition, the transmission of the upper recording layer is greater than 50% to allow for read-out and recording of the lower recording layer. This layer has high power sensitivity since the upper layer absorbs and reflects part of the incoming light. It also has a much higher reflectivity (> 50%) which after double transmission through the upper layer also results in an apparent layer reflectivity (at the disc surface) of at least 18%. These high transmission and reflectivity values have been achieved through careful optimization of the dye material and deposition, groove shapes and silver deposition. In addition to optimizing reflectivity, other parameters such as signal amplitude and tracking signals were also optimized to ensure full compatibility with current DVD standards.

The dual-layer DVD+R format book is expected to be ready within this year. Recorders for both the PC and consumer electronics markets are expected to become available during the course of 2004.