Patent ID: 7965617
Filing Date: 2011-06-21
Classification: G11B

Abstract:
1. An optical data storage medium ( 1 ) comprising a dye-based recording layer and having substantially parallel tracks for recording user information in a pattern of optically detectable marks, the tracks being provided with a guide groove, the groove being present in a user data area ( 3 ) and in an information area ( 2 ), the groove in the information area ( 2 ) having a reduced cross section compared to the cross section of the groove in the user data area ( 3 ), wherein the groove in the information area contains modulated information indicating a type of medium, the groove being trackable by a focused radiation beam ( 7 ) with a push pull method, and the value of the normalized push pull signal PPN in the unrecorded information area ( 2 ) is PPN-i and the value of PPN in the unrecorded user data area ( 3 ) is PPN-u, wherein PPN-i is lower than PPN-u.