among all the arguments about capacity, costs and copy protection for movies
I found far more interesting the following thing about the sensitive material that is going to be used for recording.
My surprise was that TDK says that they use two non-organic layers
for manufacturing their write once BD-R discs.
I don’t know if others companies that have already announced Blu-Ray discs (like Sony for example) are going to use a similar technique for their BD-R discs or not ?
Press release from TDK about manufacturing of their BD-R discs
published on January the 5th 2006:
Here is the interesting part about how the data are written and protected in the BD-R format:
For the Blu-ray Disc, which utilizes ultra-high density recording to achieve its large capacities, scratches or dirt on the disc surface can cause data errors. To ensure reliable performance, the Blu-ray Disc was first introduced to the Japanese market in a protective cartridge. The BD-R and BD-RE Blu-ray Discs that TDK is now launching utilize DURABIS 2, the company’s exclusive hard coating technology. DURABIS 2 gives the recording surface extremely high resistance to scratches, fingerprint smudges and other dirt, thus eliminating the need for a protective cartridge.
TDK’s proprietary high-precision Spin Coating manufacturing process is utilized to form each Blu-ray Disc’s cover layer, which resides atop the recording layer. Because Spin Coating creates a cover layer with nano-uniform smoothness, exceptionally stable recording and playback characteristics are realized.
The write-once type BD-R discs incorporate inorganic recording material, which is entirely different from the organic dye used in previous write-once discs.
Because the recording layer is not affected by light, the discs are exceptionally suitable for long-term archiving.
The rewritable type BD-RE discs utilize a high-sensitivity phase-change recording material that displays stability and a low error rate, even after 10,000 overwrites.
Fig. 6 Recording process with write-once type BD-R media
1. When the recording laser makes contact, its heat melts the Si and Cu alloy, which become mixed.
2. When the mixture cools, the hardened Si and Cu alloy become a composite, in which the recording mark is formed
Comparison with HD DVD still using organic dye:
http://www.cdrinfo.com/Sections/News/De ... wsId=16533
The new dye used for the discs is the result of a joint development project by Hayashibara Biochemical Laboratories, a key manufacturer of dyes for DVD-Recordable discs, Mitsubishi Kagaku Media/Verbatim and Toshiba Corporation. Development of the new dye by Hayashibara, Mitsubishi Kagaku Media/Verbatim and Toshiba is a breakthrough for HD DVD-R. Standard DVD-Recordable discs use a photosensitive organic dye as the data storage medium in their recording layer.
[b] In the transition to HD DVD, manufacturers had to meet the challenge of developing a dye for HD DVD-R discs that could be used with the narrow wavelength of a blue laser and offered sufficient readout stability.
The organic dye is highly sensitive to blue laser light, has the uncompromised readout stability essential for practical use, and the solubility in organic solvent required for easy production of the dye recording layer by a spin-coating process.
As the HD DVD-R disc is based on the same disc structure as DVD discs, back-to-back bonding of two 0.6 millimeter-thick substrates, already installed DVD-Recordable manufacturing lines can utilize the new dye in efficient production of HD DVD-R