Abstract: 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.

Abstract: A recording/reproducing apparatus comprises a disk (2) which is rotatably driven, a scratch detection circuit (6) for detecting a scratch in the disk (2) on the basis of a reproduced signal read from the disk (2) through a head (4), and a coarse movement stop control unit (14) for predicting the timing of a scratch which will appear next on the basis of the cycle of scratches detected by the scratch detection circuit (6) and stopping a coarse movement of the head (4) in a period from time immediately before at least the predicted timing to time at which the next appearing scratch passes.

Abstract: A riving current supply device for driving a stepping motor in micro steps supplies a driving current to the stepping motor for a predetermined time for each micro step, and after an elapse of this predetermined time, the driving circuit supplies a current which is smaller than the driving current and which generates a torque larger than the detent torque of the stepping motor.

Abstract: An optical pickup is provided with a limiting wall spaced a predetermined distance apart from a screw shaft to limit the separation of an interlocking projection away from the screw shaft, so that the interlocking projection cannot be disengaged from the helical groove of the screw shaft and, consequently, the screw shaft becomes unable to rotate. This state in which the screw shaft is unable to be rotated, i.e., a state where the optical pickup has bee moved to its inner limit position, can be detected through the detection of a change in the coil current of a stepping motor by a coil current measuring means or through the detection of the increase of voltage induced by the rotation of the magnet of the stepping motor to a predetermined level on the basis of the measured coil current measured by the current measuring means.