Patent ID: 7835256

Claim:
A two-layer optical disk comprising two recording layers on which a recordable spiral track is formed and recording or reproduction is performed through a transparent substrate from a same incident surface, each recording layer comprising a reproduction only pit area, an unrecorded area, an inner circumference control data recording area, and a user data recording area radially from an inner circumference side to an outer circumference side of the disc, wherein the inner circumference control data recording area of each recording layer comprises a test zone for checking a recording condition within the area and a guard zone, said test zone having a first inner circumferential address position and a first outer circumferential address position, said guard zone having a second inner circumferential address position and a second outer circumferential address position, said first inner circumferential address position of one of the two recording layers and said second inner circumferential address position of the other of the two recording layers being separated by a radial distance greater or equal to a predetermined clearance value, said first outer circumferential address position of one of the two recording layers and said second outer circumferential address position of the other of the two recording layers being separated by a radial distance greater or equal to the predetermined clearance value; and wherein each recording layer comprises a first border defined between the unrecorded area and the inner circumference control data recording area thereof and a second border defined between the reproduction only pit area and the unrecorded area thereof, the address position of the first border of one of the two recording layers and the address position of the second border of the other of the two recording layers being separated by a radial distance greater or equal to the predetermined clearance value.