Sony has unveiled two DVD Dual RW drives, the DRU-700A and the DRX-700UL. Available in early May, both drives are able to write up to 8.5GB of data to a DVD+R DL (dual layer) disc, almost twice as much as can be written to a conventional DVD.

Dual layer DVD media, otherwise known as DVD-9, has two recording layers underneath the substrate of the disc. The outermost recording layer is semi-transparent and the two recording layers are separated by a transparent spacer, thus allowing the drive to burn data to both recording layers.

The recording layers themselves are made up of a thin film of organic dye and information is recorded by permanent changes in the dye films caused by the laser in the DVD Dual RW drive’s recording head. Because the outermost layer is semi-transparent, the laser can be focused through it onto the innermost layer.

The technology was launched by the DVD+RW Alliance in November of last year. Philips and media manufacturers Verbatim and Mitsubishi Kagaku also played an important in the development of DVD+R DL.

Sony has always been at the forefront of the DVD writer market, being the first company to introduce drives that could write to both the DVD-R/-RW and DVD+R/+RW formats.

“Sony.. is one of the first to develop DVD+R DL products. With the innovative introduction of DVD+R DL, Sony offers further versatility to end users”, said Tetsuro Maekawa, marketing manager for Sony optical storage products in Europe.

There are two drives, the internal DRU-700A and the external DRX-700UL. Both are capable of writing to DVD+R DL media at 2.4-speed though there are likely to be firmware upgrades in the future that will increase the writing speed. The drives are expected to cost £149 and £249 respectively, including VAT.

At the moment, the drives are only capable of writing to the write-once DVD+R format. The DVD Forum, who is promoting the DVD-R/-RW format and of which Sony is a member, is investigating the possibility of launching a dual format DVD-R disc some time later this year.

Otherwise, the drives will write to both the DVD-R and DVD+R at eight-speed and to DVD-RW and DVD+RW at quad-speed. The package includes a comprehensive software bundle from Ahead, including Nero Burning ROM.