| 摘要 |
PROBLEM TO BE SOLVED: To provide an off-track detector capable of reducing the dispersion of the time width of off-track detection signals equivalently to the optical disk of a normal track pitch even in the optical disk of a narrow track pitch and performing a highly accurate off-track detection. SOLUTION: In the off-track detector provided with an envelope extraction means 3 and an amplification factor variable differential amplifier 5a having an amplification factor K, reflected light from a disk is converted from optical signals to electric signals in a photodetector 1 and full addition computation is performed in a full adder 2. By extracting envelope components in the envelope extraction means 3 from full addition signals and performing amplification to a sufficiently large amplitude in the amplification factor variable differential amplifier 5a, an amplitude difference between a normal disk and the optical disk of the narrow track pitch is reduced and input is performed to a binarizer 7. The off-track detection is performed in the binarizer 7, and the off-track detection is performed with fixed accuracy regardless of the track pitch of the disk. COPYRIGHT: (C)2007,JPO&INPIT
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