Patent ID: 6469965
Filing Date: 2002-10-22
Classification: G11B

Abstract:
An apparatus for selectively playing back a plurality of optical discs including a first optical disc having a recording layer positioned substantially on a surface of said first optical disc, a second optical disc having a recording layer positioned substantially in a middle position between surfaces of said second optical disc, a third optical disc having a first recording layer positioned substantially in a middle position between surfaces of said third optical disc and a second recording layer positioned substantially on one of said surfaces of said third optical disc, and a fourth optical disc having first and second recording layers positioned substantially in a middle position between surfaces of said fourth optical disc, the apparatus comprising:applying means for applying a light beam to one of said first, second, third, and fourth optical discs loaded on the apparatus; photodetector means for detecting reflected light from said one optical disc upon application of said light beam from said applying means; signal generating means for generating a signal based on said reflected light detected by said photodetector means; first detecting means for detecting a number of peaks of said signal generated by said signal generating means; second detecting means for detecting timings at which said peaks of said signal are output from said signal generating means; decision means for determining which of said first, second, third, and fourth discs is said one optical disc loaded on the apparatus based on said detected number of peaks detected by said first detecting means and said detected timings detected by said second detecting means; and setting means for setting a playback condition depending on said one optical disc loaded on the apparatus determined by said decision means.