| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that it takes time to seek an objective track since the phase relation between a gate signal for sampling a prepit and a prepit signal is deviated from the setting state until the time a spindle motor just after starting seeking is settled to a prescribed linear velocity. SOLUTION: By a BPF 9, the frequency selection is made for a wobble signal from a push-pull signal. The signal outputted from the BPF 9 is, after being made to phase data by a phase computing element 10, formed to be phase data e and frequency data f of a signal phase-synchronized with the wobble signal by a PLL consisting of a phase comparator 11, a loop filter computing element 12 and a digital VCO 13. By a prepit gate producing device 14, the phase data e are corrected with delay phase data obtained by multiplying the frequency data f by the data showing the specified signal delay times of an A/D converter 7 and the BPF 9, then, on the basis of these phase data after correction, the gate signal c for sampling the prepit signal is produced.
|
