Abstract: An optical disk apparatus includes a converging section for converging a light beam toward an information carrier; a moving section for moving the light beam converged by the converging section in a direction perpendicular to a surface of the information carrier; a light detector for detecting the light beam reflected by the information carrier; a convergence state detecting section for generating a convergence state signal representing a convergence state of the light beam at a convergence point on the information carrier and outputting a reproduction signal from the information carrier, based on the output from the light detector; a focus controller for driving the moving section to make the convergence state constant based on the convergence state signal and a prescribed target position; a reproduction quality signal detector for detecting a reproduction quality signal representing a quality of the reproduction signal based on the reproduction signal; a reproduction quality signal measuring section for cha

Abstract: A compact disc player includes an optical pickup supported by a carriage and a microprocessor for controlling the movement of a coarse actuator and a fine actuator. The coarse actuator controls the movement of the carriage and maintains its position when power is interrupted to the coarse actuator. The fine actuator is disposed between the carriage and the pickup and provides fine movement for the pickup when power is supplied to the actuator. The fine actuator moves the pickup to a neutral position when power is interrupted. A resume function is provided that restores the position of the pickup after a power interruption to its position before the interruption. A value indicative of the position of the pickup relative to the carriage is stored in memory. When power is restored to the disc player, the value is read from memory. The disc control microprocessor directs incremental movements of the fine actuator until the position of the pickup corresponds to the position represented by the stored value.

Abstract: A control system realizes a playback function by playing back stream data read out from a medium by using a decoder. When special playback functions corresponding to pause, fast forward, and rewind are to be performed, the control system moves a read start pointer to the head of a data block constructing a data format, and sets as a restart position of a playback operation.

Abstract: A storage device includes a disk medium having tracks in a plurality of guard areas which do not have ID information. Control means controls the head driving means by preventing positioning of the head to the guard areas. The device assures highly reliable and high speed access even when density is high by ensuring movement and positioning of the head across the storage medium in data areas which have ID information.

Abstract: An optical disk apparatus for recording data on a track formed on an optical disk and reproducing data recorded on the track includes a rotation means for rotating the optical disk at a predetermined speed, an irradiation means for irradiating the optical disk with a light beam for data recording and data reproduction, a recording means for irradiating the optical disk rotated by the rotation means at the predetermined speed with the light beam provided from the irradiation means to record data from a first point to a second point along the track in units of sectors, a reproduction means for irradiating the optical disk rotated by the rotation means at the predetermined speed with the light beam provided from the irradiation means to reproduce data from the first point to the second point along the track in units of sectors, and a setting means for setting the distance from the first point to the second point along the track to {(track length corresponding to n (n natural number) turns of the disk)&minus