METHOD FOR IDENTIFYING TYPE OF TWO-LAYER DISC AND OPTICAL DISC DEVICE

摘要

There is provided a method for readily and accurately identifying the type of a two-layer disc (write once two-layer disc, rewritable two-layer disc, ROM type two-layer disc). The method for identifying the type of a two-layer disc comprises a step for irradiating each layer of a two-layer disc loaded into an optical disc divice with light of different wavelengths under focused state and determining the reflectivity for the light of each wavelength, and a step for identifying a write once two-layer disc, a rewritable two-layer disc, and an ROM type two-layer disc depending on the combination of reflectivity for the light of respective wavelengths. It is preferable that one light have a wavelength for a DVD-based disc and the other light have a wavelength for a CD-based disc.