Abstract: In a seek operation, in which a head is moved to a target track, the detection output of a head-position detection unit is integrated in each track. Each integrated value is a positive or negative value proportional to an offset given to a center value obtained from the maximal value and the minimal value of the detection output. The center value is compensated for by a compensation value obtained by multiplying the integrated value by a coefficient. As a result, the offset is reduced and a highly precise positional detection is allowed.

Abstract: After data recording or reproduction is finished, servo control is stopped within a predetermined time to disable a positional compensation output to a head. While servo control is being stopped, servo data recorded in a medium is monitored. When the head is moved on the medium further than a predetermined distance, servo control is activated to start a positional compensation output to the head. The stop/start of the servo control is implemented by software embedded in the CPU of a disk apparatus.

Abstract: A track-follow control device uses a positional error signal representing the positional error between a target track on a recording medium and a head for recording information to or reproducing information from the recording medium. The track-follow control device controls an actuator to follow the target track by means of a signal from a sub-controller for outputting a correction signal by using its gain circuit for performing gain correction in accordance with an output result from a main-controller for outputting a positioning control signal to the actuator and a band-pass filter for allowing the passage of a predetermined frequency of the positional error signal. The sub-controller extracts only an eccentric frequency, which prevents the correction signal from breaking.

Abstract: An optical recording and/or reproducing apparatus employing a stepping motor for driving an optical pickup for movement in radial directions of a disk. The frequency of a driving pulse signal for driving the stepping motor is lower than the resonant frequency of a transmission system for transmitting the driving force of the stepping motor to the optical pickup and higher than the reproducing feed speed.

Abstract: A stepping motor driver drives, for example, a stepping motor incorporated into an optical recording/reproducing apparatus to move an optical pickup in the radial direction of an optical disk during a seek operation. A current measuring device measures a current flowing through the stepping motor, and a control circuit changes the excitation phase of the stepping motor on the basis of the variation of the current detected by the current measuring device.