Patent ID: 8358568

Claim:
An optical disc reproduction power setting method for determining a reproduction power setting in an optical disc reproduction method for reproducing information from an optical disc by irradiating the optical disc with laser light, the optical disc reproduction power setting method comprising: a test reproduction step for carrying out test reproduction of an area in which information is recorded on the optical disc, using a test reproduction power higher than a laser light reproduction power used in reproduction from the optical disc; a life-span index calculating step for determining a reproduction time or reproduction count until reproduced signal quality degrades to a prescribed value in the test reproduction step as a life-span index; and a reproduction power determining step for determining, as an optimum reproduction power, from a relation between the life-span index and the test reproduction power when test reproduction is carried out using at least three mutually differing test reproduction powers, a laser light power such that even if reproduction from the optical disc is carried out for a prescribed time or count, an amount of degradation of the reproduced signal is equal to or less than the prescribed value, and using this power as a reproduction power setting; wherein the reproduction power determining step includes an approximation step for approximating the relation between the test reproduction power and the logarithm of the life-span index obtained in the life-span index calculating step with an approximation curve comprising a first straight line section having a form of a straight line asymptotically approaching a first slope, a second straight line section having a form of a straight line asymptotically approaching a second slope more gradual than the first slope, and having the same direction as the first slope, and a curve section that connects the first straight line section and the second straight line section, and based on the approximation curve obtained by the approximation step, a laser light power at which the amount of the degradation of the reproduced signal reproduced from the optical disc is equal to or less than the prescribed value after the optical disc has been reproduced for the prescribed reproduction time is determined as the optimum reproduction power.