Patent ID: 6226244
Filing Date: 2001-05-01
Classification: G11B,H04N

Abstract:
A playback apparatus for recovering information recorded on a record carrier, the record carrier exhibiting (i) first variations of a first physical parameter of the record carrier, said first variations corresponding to the recorded information, and (ii) also exhibiting, when provided therewith, second variations of a second physical parameter of the record carrier, the second physical parameter differing from the first physical parameter; said apparatus comprising:a transducer for scanning the record carrier and outputting a detection signal, said detection signal having first variations in response to said first variations of said first parameter, said detection signal also having second variations in response to said second variations of said second parameter, said second variations of the detection signal having a frequency spectrum which is outside the frequency spectrum of said first variations of the detection signal;recovery means coupled to said transducer and responsive to said first variations of the detection signal to recover the recorded information therefrom;detection means also coupled to said transducer and responsive to said second variations of the detection signal to produce an output signal indicating whether the record carrier is provided with said second variations of said second parameter; andenabling means coupled to said detection means for enabling said recovery means to recover the recorded information only when the output signal of said detection means indicates that the record carrier is provided with said second variations of said second parameter.