| 摘要 |
PROBLEM TO BE SOLVED: To adjust the focusing servo by detecting the amount of jitter in an optical disk drive. SOLUTION: The reflected light from an optical disk 10 is converted into RF signals in the optical pickup 12, amplified in an RF amplifier 14, and supplied to an equalizer 16. The RF signals boosted in an equalizer 16 are made binary in a thresholding section 18. The jitter detecting section 22 detects the phase shift between the binary signals and the reference clock signal generated in the PLL section 20. It, however, does not detect the phase shift of all the signals over 3T to 11T of the binary signals but detects the phase shift of only the 3T frequency as the amount of jitter. Thus, the correct amount of jitter can be detected and the optical pickup 12 can be adjusted to minimize the amount of jitter.
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