Patent ID: 7636295

Claim:
An optical information recording medium comprising: a land/groove structure having a land and a groove in which information is recorded in tracks on both the land and the groove, and the recording can be performed at a plurality of linear velocities; wherein a ratio of a maximum recordable linear speed to a minimum recordable linear speed has a value of 2 to 3; a ratio of an amount of light reflected from a groove in an unrecorded state to an amount of light reflected from a land in an unrecorded state has a value of at least 1.08 and no more than 1.19; the recording or reproduction of information is performed by utilizing a phase change in the land/groove structure, a ratio of a groove half-value width to a track pitch is greater than about 0.5 and less than about 0.6; and a depth of the groove is from 40 to 65 nm.