| 摘要 |
<p>[PROBLEMS] To provide an optical disc apparatus wherein even when channel frequencies are switched due to a seek or even when there exists an unwritten area just before, a data recording area, in which data have been recorded at high densities, can be read from the front of the data recording area without errors. [MEANS FOR SOLVING PROBLEMS] An FM demodulator (6 of Fig.1) continuously detects the frequency of a second signal to acquire frequency information (Fwbl), and a signal, which is obtained by adding an output (?F) of a loop filter (52 of Fig. 1) to the frequency information (Fwbl), is used as a control input of a local oscillator (53 of Fig. 1) in a PLL loop (5 of Fig. 1) receiving a first signal as its input. A fast phase pull-in can be achieved by using the second signal, the frequency information of which can be always acquired, to control the center frequency of the local oscillator (53 of Fig. 1).</p> |
