Akiyoshi Inoue

Organic Dye 25 GB Write-Once Disk with In-Groove Structure

We have developed a new write-once disk technology, which is applicable to the Blu-ray disc system. An organic dye was adopted for the recording layer, which was optimized for the recording of the laser diode wavelength of 405 nm. We adopted a concave in-groove for the recording tracks to avoid thermal interference with adjacent recording tracks due to undesired and uneven dye pooling between adjacent tracks, considering the advantage of fabrication by spin-coating. We optimized the in-groove structure for low-to-high modulated recording. A sample disk, which was made by the conventional spin-coat process, showed good recording and readout characteristics with remarkably low cross-talk and cross-writing.

THE NEW RE-WRITABLE DISC SYSTEM FOR DIGITAL VERSATILE DISC

The authors have developed a new re-writable disc system named digital versatile disc (DVD)-RW. The basic concept of this system consists of the following characteristics. 1) This system has added a re-writable feature to the DVD-R (write once system). 2) It is compatible with DVD-ROM, DVD-Video and DVD-Audio systems. By capitalizing on the characteristics of this system as much as possible, it will be possible to produce a useful standard, meeting the users demand for video recording application of the DVD.

4.7 GB Phase Change Optical Disc with In-Groove Recording

We developed a rewritable optical disc with 4.7 GB/side capacity as an extension of the digital versatile disc recordable (DVD-R) system. The disc is readily playable on a read-only DVD player or a DVD-ROM drive with a small firmware modification. As far as the fundamental characteristics of the disc which adopts an in-groove recording are concerned, the reflectivity is 18% or more, modulated amplitude is 60% or greater, and jitter is 8% or less. As we had sufficient differential phase detection (DPD) tracking error signals from the recorded disc, we think the DPD tracking method is practical. These results cleared the single-layer DVD-ROM specifications except for the reflectivity. The measured reflectivity satisfies the specifications of the dual-layer DVD-ROM disc. Furthermore we confirmed that the recorded disc was playable on a blue laser playback system.