Patent ID: 7830778
Filing Date: 2010-11-09
Classification: G11B

Abstract:
1. An optical information recording medium having a single optical recording layer and a single optical reflection layer, comprising: a disk-shaped substrate in which spiral grooves are formed on one main surface; the optical reflection layer formed at the main surface of the substrate with grooves corresponding to the grooves of the substrate for reflecting a laser beam; the optical recording layer, formed on the optical reflection layer, containing an optical absorption material comprising an organic dye that absorbs the laser beam, said optical reflection layer and said optical recording layer being formed on the substrate in this order for providing a function of increasing the reflectivity of the laser beam and improving the recording and playback characteristics of the optical recording layer; a protective layer formed on the optical recording layer; and an optical transparency layer formed on the protective layer, wherein the optical recording layer comprises a main information area for recording optically readable main information by the irradiation of a laser beam and a Burst Cutting Area (BCA) as a sub-information area on the inner circumferential side of the main information area for recording sub-information different with respect to a type from the main information; and wherein a track pitch TrB of grooves formed in the sub-information area is different from that of grooves formed in the main information area and is about 0.32 μm or less, and the depth D and the half-band width W of the grooves of the optical reflection layer in the sub-information area satisfy a relation represented by: W≧2D+70, said relation being such that a difference between a reflectivity R