What Is Blu-ray Disc?

BD-R 25GB	BD-R 50GB	BD-RE 25GB	BD-RE 50GB
BD-R (write-once type)		BD-RE (rewritable type)

TDK Corporation has commenced shipments of mass-production samples of so-called bare-type (i.e., cartridge-less) versions of its BD-R (write-once type) and BD-RE (rewritable type) Blu-ray DVD media. The four new products include the BD-R25 (single-side, single-layer, 25GB) and BD-R50 (single-side, dual-layer, 50GB) write-once types and BD-RE25 (single-side, single-layer, 25GB) and BD-RE50 (single-side, dual-layer, 50GB) rewritable types.

For the Blue-ray Discs, which achieves significantly higher density recording, scratches or dirt can have fatal consequences to the data, so it was initially introduced utilizing a protective cartridge. The BD-R and BD-RE Blu-ray Discs launched this time make use of DURABIS 2, TDK's originally developed hard coating technology. This achieves a recording surface with extremely high resistance to scratches and dirt (particularly fingerprint smudges), thus enabling anxiety-free use of a cartridge-less disc.

For the forming of the cover layer above the disc's recording layer, an original high-precision spin coating is utilized, realizing smoothness at the nano-level while achieving stabilized recording and playback characteristics.

The BD-R write-once type, moreover, makes use of an inorganic material in the recording layer, entirely different from the organic dye used in previous types of write-once type discs. Because the recording layer is not affected by light, it realizes a disc with outstanding archivability. Furthermore, the BD-RE rewritable type utilizes a high-sensitivity phase-change material that realizes stabilized characteristics, in the form of a low error rate, even after 10,000 overwrites.

In addition, the single-sided, dual-layer disc realizing 50GB capacity harnesses high-precision stacking technology resulting from years of work at optical disc development, to achieve precision forming of its respective functioning layers. The upper layer (Layer 1) and lower layer (Layer 0) are combined in terms of high sensitivity and recording layer transparency ratio, realizing stabilized recording and playback characteristics.

The commitment of TDK's advanced optical disc technology has resulted in creation of the world's first 25GB and 50GB high-capacity discs capable of 2X recording speed. TDK is confident that the BD-R and BD-RE, freed from the confines of a cartridge, will offer their large capacities with greater facility, thus greatly expanding the potential of optical recording.