Patent ID: 7327657

Claim:
A reproduction signal evaluation method comprising: a first step of playing an information recording medium on which digital information is recorded with record marks having various sizes by using optical means, and obtaining a reproduction signal reflecting the digital information; a second step of obtaining a first reproduction signal, of signals contained in the reproduction signal, which reflects digital information recorded with a record mark having a largest size; a third step of obtaining a second reproduction signal, of signals contained in the reproduction signal, which reflects digital information recorded with a record mark having a predetermined size other than a record mark having a smallest size; a fourth step of obtaining an evaluation value on the basis of the first and second reproduction signals; and a fifth step of evaluating a characteristic of the reproduction signal on the basis of the evaluation value; wherein the second step comprises obtaining an amplitude central level of the first reproduction signal, the third step comprises obtaining an amplitude central level of the second reproduction signal, and the fourth step comprises obtaining an evaluation value based on a value calculated by dividing a difference between the amplitude central levels of the first and second reproduction signals by a difference between a high level and a low level of the first reproduction signal.