| 摘要 |
PROBLEM TO BE SOLVED: To generate highly sensitively a pre-pit signal for detecting a pre-pit from the light receiving signal of an optical disk. SOLUTION: A pre-pit detecting device has a light receiving plane (not illustrated) divided into a plurality of regions including a plurality of pre-pit detecting regions and receiving reflected light from an optical disk, a signal generating means (not illustrated) for generating a plurality of light receiving signals in accordance with light quantity of respective reflected light of a plurality of pre-pit detecting regions, a reproduced signal eliminating means (addition circuit 15, gain adjusting circuit 17, differential circuits 18, 19) for eliminating a reproduced signal recorded in an information track from the plurality of light receiving signal, a delay circuit 20 for adjusting phase difference of a plurality of light receiving eliminating signals in which a reproduced signal is eliminated by the reproduced signal eliminating means, and a differential circuit 21 for generating a pre-pit signal from difference of a plurality of light receiving adjusting signal in which phase difference is adjusted by the delay circuit 20. COPYRIGHT: (C)2004,JPO&NCIPI
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