Patent ID: 7540006
Filing Date: 2009-05-26
Classification: G11B

Abstract:
1. An optical information recording medium comprising: one or more information layers including a recording layer for recording/reproducing an information signal by irradiation with a laser light; and a separating layer or a protective substrate on which a first information layer of the information layer on the irradiation face side is formed, the separating layer or the protective substrate having a guide groove spirally or concentrically formed on a surface thereof, respective inclined planes on the inner perimeter side and the outer perimeter side of the guide groove having inclined angles α and β with respect to a bottom face of the guide groove, the guide groove having two or more dissymmetric regions in the radius direction where the inclined angles α and β are different, wherein the dissymmetric regions comprise first and second dissymmetric regions having the following relations: α-β≦10 degrees in the first dissymmetric region, and α-β≧20 degrees in the second dissymmetric region.