Optical disk drive having means for preventing inner reference clock signal in PLL circuit from being disturbed when defective portion is read

摘要

An optical disk drive includes a voltage-controlled oscillator for generating an inner reference clock signal; a data extraction section for extracting data from a reproduction (RF) signal read from a disk medium with the use of the inner reference clock signal; a phase comparator for comparing the RF signal in phase with the inner reference clock signal to send a phase error signal to the voltage-controlled oscillator; a frequency comparator for comparing in frequency the RF signal with the inner reference clock signal to send a frequency error signal to the voltage-controlled oscillator through a switching unit; and a defect detection section for detecting a defective portion on the disk medium from the envelope of the RF signal to output a defect detection signal. The switching unit is switched so as to break a connection between the voltage-controlled oscillator and the frequency comparator when the defect detection signal is output.