Abstract: A disk drive apparatus for recording (writing) and/or reproducing (reading) information on an optical disk by rotating the optical disk, and adjusting the tilt angle of an optical pickup device with respect to the optical disk. A spindle chassis rotationally supports a turntable on which the optical disk is placed. A pickup chassis, rotationally supported on said spindle chassis, movably supports an optical pickup device that writes and/or reads the information to/from the optical disk and is movable toward and away from the turntable. A tilt mechanism adjusts the tilt angle of the optical pickup device with respect to the optical disk by rotating the pickup chassis with respect to the spindle chassis.

Abstract: Apparatus for providing fine search in a sled movement mechanism employing a stepping motor by controlling the speed with which the head jumps in succession to next neighboring tracts on a disc and by causing pickup movement accurately for a distance corresponding to the distance of movement of the objective lens to realize the fine search in the sled movement mechanism employing the stepping motor. Also, the distance of head movement in the radial direction of the disc can be prescribed and, upon interruption of the head jumping operation, the head can be subsequently transported a distance corresponding to the target number of track jumps.

Abstract: When a signal is played back from an injured portion of an optical disk, immediately after the reproduction of the signal from the injured portion, a mirror signal can be obtained with a high degree of accuracy from conversion of a traverse signal into a binary signal. In a traverse-signal discriminating circuit, a traverse signal, a low-frequency component of a playback signal, is separated from the playback signal and then supplied a hold circuit. In the hold circuit, the bottom of the traverse signal is held in order to produce a bottom hold signal. In a defect detecting circuit, in the mean time, a defect in the playback signal, if any, is detected. If a defect is detected, the defect detecting circuit outputs a defect signal at an H level to a hold-voltage resetting circuit. The hold-voltage resetting circuit discharges a capacitor included in the hold circuit, halting the operation to hold the bottom of the traverse signal as long as the defect signal supplied thereto is set at the H level.

Abstract: A track count pulse generating apparatus is provided which can correctly generate track count pulses to accurately count the number of tracks on a variety of optical disks having track pitches different from each other.