Patent ID: 7355957

Claim:
A disc-shaped optical disc medium on which a spiral-shaped recording track is formed, said optical disc medium comprising a data recording area and a system information recording area which are set thereon with said optical disc medium divided in a radial direction thereof, wherein recording density of information on said system information recording area is lower than that of data on said data recording area wherein said system information recording area lies in an inner peripheral side of said optical disc medium, wherein said system information recording area has a shortest pit length which is substantially integer times as large as that of said data recording area, wherein said data recording area has a shortest pit length L 1 of data to be recorded or reproduced that satisfies a relationship of L 1 <0.35Ã—Î»/NA, where Î» represents a wavelength of a light source for using recording/reproducing and NA represents a numerical aperture of an object lens, and said data recording area has a signal quality evaluation index value (PRSNR) value defined by quality evaluation index in a partial-response maximum-likelihood (PRML) that is not less than fourteen; said system information recording area having a shortest pit length L 2 of data to be exclusively reproduced that satisfies a relationship of L 2 >0.50Ã—Î»/NA; and said system information recording area having a track pitch which is wider than that of said data recording area.