Tsuyoshi Komaki

150 GB, 6-Layer Write Once Disc for Blu-ray Disc System

This report is on a 50 GB 6-layer write once disc with the newly developed recording materials for blu-ray disc system. We achieved the optimum recording powers and the jitter values less than 160 mW and 8.0% for each layer at the user data recording rate of 72 Mbps. This result shows feasibility of realization of 6-layered recordable blu-ray disc

The Phase Change Optical Disc with the Data Recording Rate of 140 Mbps

We have been developing a new phase change optical disc on the base of the recording system (DVR) with a blue laser (405 nm) and dual objective lens with a numerical aperture (NA) of 0.85. We have achieved the data recording rate of 140 Mbps. The significant techniques to achieve the recording rate as follows: rearrangement of the AgInSbTeGe composition for the rate of 140 Mbps and controlling the re-crystallization by SRC structure (the super-rapid cooling structure) and development of Write Strategy for the high data recording. As a result of the techniques, less than 10% jitter value and more than 1,000 times overwriting possibility at 140 Mbps have been achieved.

Inorganic write-once disc with quadruple recording layers for Blu-ray Disc system

The optical disc with larger capacity and higher speed data recording rate will be required in coming broadband network society. We have developed the inorganic write-once disc with quadruple recording layers for the blu-ray system. We obtained the reflectivity of more than 5% and a jitter value of less than 10% for each recording layer. As a result, we proved the possibility of 100 GB user capacity of 120 mm diameter size.

High-Performance Hard Coat for Cartridge-Free Blu-ray Disc

A practical way of realizing cartridge-free Blu-ray disc using nanocomposite UV-curable resin as a hard coat on a laser incident surface of the disc is described. The hard coat is a composite material of UV-curable acrylic resin and nanoparticles of silica. A lubricant that exhibits oil repellency as well as low friction coefficient was added to the hard coat in order to facilitate the removal of fingerprints. It effectively prevents abrasions, scratches and problems of fingerprints on the disc surface. Abrasion and scratch resistances, and ease of fingerprint removal were evaluated and compared with those of a polycarbonate surface and a conventional UV-curable hard coat.

Functional hard-coat for cartridge-free DVR-blue

Optical discs with larger storage capacity and higher data recording rates are required for the coming digital network society, for example, to realize non-linear editing and long term data archiving on broadcasting tasks. We have been developing a new phase change optical disc, which has much higher data recording rate of up to 140 Mbps (T. Kato et al, Tech. Dig. ISOM2001, pp. 200-201, 2001), based on the DVR system (/spl lambda/=405 nm, NA=0.85, cover layer thickness=100 /spl mu/m) (Y. Kuroda et al, 1999; M.J. Dekker et al, 2000; Y. Kasami et al, 2000). As a general rule, the smaller the laser spot size on the disc surface, the more sensitive the disc becomes to scratches or fingerprints on it. In such a system, the distance between the disc surface and objective lens (i.e. working distance) is very narrow due to a high NA. Therefore it is also feared that the objective lens hits the disc surface due to an external impact. To avoid these problems when the disc is taken out of a cartridge, we have developed a new hard-coat. The cartridge-free DVR-blue disc was expected to be accomplished by the following properties: (1) abrasion resistance; (2) scratch resistance; (3) water and oil repellency (low surface free energy). Among these properties, the abrasion resistance is considered to be the most important.

Spin-Coating Technology of the Cover Layer for Digital Video Recording-Blue Disc

We have achieved the cover layer thickness distribution of 100±1.5 µm on a disc by improving the spin-coating method and developing an original spin-coating machine. The small skew of the disc is achieved by using a newly developed UV-curable resin.