| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus position adjustment method capable of obtaining good recording/reproducing characteristics together with a land track and groove track. SOLUTION: While discerning whether the laser beam spot is positioned on the land track or the groove track according to the L/G switch signal LGS from the land groove detection unit 34, the focus position rough detection unit 50 and the focus position precise detection unit 60 detect two new focus positions (for the land and the groove) so that the bit error rate BER that is measured in the error rate measurement unit 33 and the envelope of and the jitter in the reproduction signal RF would improve, and output two control signals (FBAL and FOFF) for changing the control target position into the new two focus position to the focus error detection unit 36. COPYRIGHT: (C)2006,JPO&NCIPI
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