Patent ID: 7248547

Claim:
A defect signal detecting apparatus for an optical recording/reproducing apparatus, comprising: a maximum value detecting unit for detecting a highest amplitude among input signals during a maximum value detection period as a maximum value based on a reference maximum value; a minimum value detecting unit for detecting a lowest amplitude among the input signals during a minimum value detection period as a minimum value based on a reference minimum value; an asymmetry detecting unit for calculating an amount δ of asymmetry by detecting a maximum value I L max and a minimum value I L min of a signal I L that has a maximum periodicity among the input signals, and by detecting a maximum value I S max and a minimum value I S min of a signal I S that has a minimum periodicity among the input signals; and a defect determining unit for determining whether there is a defect in the input signals, using the maximum value, the minimum value and the amount δ of asymmetry, wherein the defect determining unit determines a defect signal and outputs a corresponding blank signal if a ratio of the maximum value to the minimum value is higher than 1+Δ−δ, or lower than 1−Δ−δ, where Δ is a margin of the ratio of the maximum value to the minimum value.