Michihiro Shibata

A New Type of Light Stabilizer for Dye Layers of Optical Disks: Tetracyanoquinodimethane Derivatives

A new technology to improve the light fastness of cyanine dye layers of a compact disk recordable (CD-R) or a digital video disk recordable (DVD-R) without using any singlet oxygen quenchers was discussed. The light fastness of dicarbocyanine dye layers of a CD-R was improved by doping with tetracyanoquinodimethane (TCNQ) derivatives of various reduction potentials (E1/2RED). The optimum potential was found to be around 0 V vs saturated calomel electrode (SCE). Doping with TCNQ derivatives was found to be effective also for the improvement of light fastness of the carbocyanine dye layers which have optical properties suitable for a DVD-R disk. Excessive electron demanding TCNQ derivatives (E1/2RED> 0), however, showed rather poor jitter and block-error rate (BLER) after exposure to a xenon lamp as compared to a TCNQ derivative (TCNQ1) with an optimal reduction potential (ca. 0 V vs SCE). Since TCNQ derivatives have no absorption band in a red to near infrared region, the CD-R or the DVD-R having cyanine dye layers doped with TCNQ derivatives exhibit higher reflectivity than those with such singlet oxygen quenchers as diimmonium salts.

Progress in organic write-once technology for Blu-ray disc-recordable and DVD-R media

A new recording mechanism that generates well-defined cavities in recording pits is found to satisfy essential performance criteria for high-density, high-speed recordable dye media. A 0.1mm cover layer with a web-coated protective layer is shown to have satisfactory resistance to abrasion and scratching, and to offer ease of fingerprint removal.

A 11?177 Mbps Recordable Digital Versatile Disc (1?16? DVD-R) Using a New Dye

The possibility of 11 to 177 Mbps (1× to 16×) speed recording was confirmed by the investigation of the recordable digital versatile disc (DVD-R) using a new oxonol dye. Low jitter and a high aperture ratio (AR) even after high-speed recording are attributed to the unique thermal decomposition behavior of the dye, i.e., its low decomposition temperature, small heat generation and well defined void generation. The dye neither contains toxic heavy metals nor corrodes a pure silver reflective layer.

Improved Thermal Stability of Dye-Based Optical Discs: Effect of Hydrogen Bonding

To improve the stability of dye-based optical discs during long-term storage, we examined the effect of hydrogen bonding in the dye layer with the expectation that the strong networks of hydrogen bonds would suppress the migration of chemical species, thereby preventing changes in the properties of the amorphous dye films. Intermolecular hydrogen bonding was compared in six dyes, which were composed of a combination of an indodicarbocyanine-dye cation and six colorless naphthalenedisulphonate anions with zero to two hydroxyl groups. Accelerated temperature/humidity testing revealed that the introduction of hydroxyl groups on the colorless anions improved the stability of the cyanine-dye-based optical discs. The error rate was very low, particularly when a thermally stable network of hydrogen bonds involving the hydroxyl (–OH) groups was present, as confirmed by variable-temperature IR spectroscopy. This stabilization due to hydrogen bonding affords a new guideline for designing dyes for optical discs.

Feasibility of high-speed recording on oxonol dye double-layer recordable digital versatile discs produced by inverted stack method

The feasibility of high-speed recording on oxonol dye double-layer recordable digital versatile discs (DVD+R DL and DVD-R DL) produced using the inverted stack method was investigated. Jitter of less than 9% was achieved at 2.4–16× recording speeds on DVD+R DL discs, and a high aperture ratio (AR) and jitter of less than 8% were achieved at 2–12× recording speeds on DVD-R DL discs. From these results it was concluded that oxonol dye is suitable for high-speed recording on DVD+R DL and DVD-R DL discs. Recording principles of the L1 layer were also investigated.