US Patent 7843786 Discrimination method of optical storage medium

A method for discriminating an optical storage medium is disclosed. A predetermined range of the optical storage medium is read after the light source is focused on; and thereby a plurality of data transition points and transition regions defined by an interval of two neighboring points are obtained. Thereafter, the time-consumption for reading the longest transition region is used to determine the type of the currently accessed optical storage medium. Another physical characteristics according to data storage formats, such as the PLL clock frequency or the distance between the reflection layer and the surface layer of the optical storage medium, may be used as references to discriminate the currently accessed optical storage medium.