| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk drive which can reproduce the recorded high density data from the beginning without errors even when the channel frequencies are changed by seeking or when there are non-recorded areas right in front. SOLUTION: This drive continuously detects the frequency (Fwbl) of the 2nd signals by using an FM demodulator (6 in Fig.1), and uses the sum of the output (ΔF) of a loop filter (52 in Fig.1) and (Fwbl) as the control input signals of the local oscillator (53 in Fig.1) in the PLL circuit (5 in Fig.1) inputting the 1st signals. The phase is pulled in within a short period by controlling the center frequency of the local oscillator (53 in Fig.1) by using the 2nd signals that the frequency information can always be obtained. COPYRIGHT: (C)2007,JPO&INPIT
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