PLAYBACK APPARATUS WITH SECOND VARIATION DETECTION

摘要

PROBLEM TO BE SOLVED: To provide a playback apparatus which needs no additional component such as a phase-locke loop means. SOLUTION: Information is recorded in an information carrier 2 in the form of variations of a first physical parameter. The playback apparatus scans the information carrier by a transducer 4 to respond to the variations of the physical parameter. An information recovering circuit 5 recovers the information from a first detection signal D1 received from the transducer 4. The information recovering circuit 5 has a phase-locked loop 51. The information carrier 2 exhibits a second variation of a second physical parameter which differs from the first physical parameter but which is detectable by the transducer 4. A detection circuit 6 detects the presence of the second variance based on a second detection signal D2 received from the transducer 4. The detection circuit 6 is capable of using the phase-locked loop of the information recovering circuit 5 to detect the presence of the second variance. COPYRIGHT: (C)2009,JPO&INPIT