| 摘要 |
PROBLEM TO BE SOLVED: To detect an accurate amplitude level from area head part at a switching position of a recording area on a disk in which the DC level of a RF signal is changed. SOLUTION: A top envelope detecting circuit 10 detects the top envelope value of the RF signal read out with an optical head 2, a bottom envelope detecting circuit 11 detects the bottom envelope value of the RF signal. A difference circuit 12 calculates the amplitude level of the RF signal from difference between the top envelope value and the bottom envelope value, a compulsion discharge circuit 15 resets the detected top envelope value and the bottom envelope value, in a boundary area in which the DC level of the RF signal recorded in the optical disk is different. COPYRIGHT: (C)2008,JPO&INPIT
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