Kenji Yoneyama

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.

Antifingerprint property of the hard coat for cartridge-free Blu-ray Disc

We made improvements on the previously reported hard-coat for cartridge-free Blu-ray disc from a viewpoint of an anti-fingerprint property. As a result of this study, two types of the hard-coat have been obtained. One is for Blu-ray discs of ROM and write-once types, and the other is for that of rewritable type. The former well inhibited a deterioration of bit error rate (bER) of the signal written prior to the fingerprint adhesion. The later exhibited low bER for the data signals written both before and after the fingerprint adhesion. These results are attributable to the area ratio of drops of fingerprint-ingredient on the disc surface, and the low area ratio resulted in a low bER. Moreover, it was confirmed that the disc with higher contact angle of oily compound exhibited the lower area ratio of the fingerprint.