TDK Corporation has announced it will begin shipments of two new BD-R (write-once type) Blu-ray Discs capable of recording at 4x speed. TDK 4x 25GB BD-R Blu-ray Disc media and the 50GB version will both begin shipping later this summer.

Needs for the Blu-ray Disc, a recording- and storage-use media that can accommodate high volumes of data such as high-definition images, have been growing rapidly. TDK's new discs, by achieving a 4x recording speed, will enable recording times to be reduced by half from the previous discs (with 2x recording speed), making the use of high-capacity optical discs even easier.

In April 2003, TDK launched sales of the BD-RE120N (rewritable type, enclosed type cartridge) for recording use, and followed in November 2004 by the BD-RE135N (rewritable type, open-type cartridge). In April 2006, the company simultaneously launched of the BDD-R25S (write-once type, cartridgeless) and BDD-RE25S (rewritable-type, cartridgeless), the world's first "bare-type" Blu-ray Discs, worldwide.

The BDA (Blu-ray Disc Association) has certified the standards of the new write-once-type Blu-ray Discs, including 4x recording capability, paving the way for their commercialization for general consumers.

The new TDK BD-R discs, compatible with 1x ~ 4x recording speeds, like its predecessor (BD-R) with 1x ~ 2x capability, utilize a recording layer composed of inorganic material in a metal dual-layer structure. They also adopts TDK's DURABIS 2 hard coating technology, smooth cover layering technology formed by high-precision spin coating, and other original TDK technologies, enabling creation of high-reliability discs.

The discs are manufactured at TDK's Chikumagawa Techno Factory at Saku City, Nagano Prefecture.

Main Features of TDK 4x Blu-ray Discs

1. 4x recording compatible: Reduces recording time by half compared to 2x disc.

A recording layer boasting high sensitivity is utilized for compatibility with 4x recording (144Mbps transfer rate). 4x recording reduces recording time by half compared with the previous 2x disc. 4.7GB of data can be copied in less than 5 minutes, which is comparable to a DVD-R recording speed of 16x.

2. DURABIS 2 coating provides significantly greater resistance to scratches and dirt (particularly fingerprint smudges), ensuring safe use even without a cartridge.

Since the area of the laser spot on the Blu-ray Disc is small (about one-fifth that of the DVD), scratches or dirt on the recording surface can have an especially detrimental effect, causing errors. DURABIS 2 overcomes the issue by offering significantly higher resistance to scratches, and exceptional resistance to dirt and grime (particularly fingerprint smudges).

3. Exclusive, high-precision spin coating creates a cover layer with nano-precise smoothness for breakthrough stability.

The precision and smoothness of the cover layer is extremely important, because the laser beam must cleanly pass through the cover layer in its path to the recording layer. To form this cover layer, TDK utilizes an exclusive high-precision spin coating method. The thickness of the cover layer is controlled to the nano-level. As a result, the load on the focus servo circuit used to correct laser beam positioning is reduced, enabling breakthrough stability.

4. Recording layer utilizing inorganic material in a metal, dual-layer structure is unaffected by exposure to light, giving it outstanding archivability.

Previous write-once optical media such as CD-R and DVD-R utilized organic dye for their recording layers. Write-once type BD-R media is based on a completely new concept for the recording material wherein a two-layer structure composed of silicon (Si) and copper alloy (Cu) inorganic materials is utilized. When heated by the recording laser beam, these melt and the Si and Cu alloy become a composite to form recording marks. Because the material is inorganic, it is not affected by light, and offers superior archivability.