Patent ID: 7301877

Claim:
An information recording medium comprising a track in which information composed of a plurality of codes different in length is recorded, wherein the next shortest code after the shortest code included in the plurality of codes if formed on the track so that the result of evaluating a reproduced signal based on the reproduced signal of the next shortest code satisfies a specific evaluation level, wherein if the maximum value of the reproduced signal of the shortest code reproduced from the information recording medium is IaH and the minimum value of the reproduced signal is IaL, the maximum value of the reproduced signal of the next shortest code after the shortest code reproduced from the information recording medium is IbH and the minimum value of the reproduced signal is IbL, and the amplitude of the reproduced signal of the longest code or a code three times or more as long as the shortest code reproduced from the information recording medium is Ic, the maximum value of the reproduced signal is IcH, and the minimum value of the reproduced signal is IcL, the absolute value of {(IbH+IbL)/2−(IaH+IaL)/2}/Ic×100 is smaller than the absolute value of {(IcH+IcL)/2−(IbH+IbL)/2}/Ic×100.