Abstract: An optical disk unit for recording information on and reproducing information from a disk recording medium by projecting a light beam thereonto includes a signal level detection part detecting a level of a track error signal generated based on reflected light of the light beam from the disk recording medium, a scattered light detection part detecting scattering of the reflected light, and an off-track detection part which detects an off-track of the light beam using detection signals supplied from the signal level detection part and scattered light detection part.

Abstract: The present invention provides an information storage apparatus generating a tracking error signal in which apparatus and method the differential push-pull method is applied to a three spot method using a main beam and two sub-beams, the main beam for writing data on a recording medium and reading data from the recording medium, the information storage apparatus including the following parts. A beam moving part moves the main beam from a blank track to a recorded track. A center value calculating part calculates a center value of the tracking error signal when said main beam is moved from the blank track to the recorded track so that a reference value of the tracking error signal is corrected in accordance with the center value when said main beam writes data on the recording medium.

Abstract: An optical disk unit for recording information on and reproducing information from a disk recording medium by projecting a light beam thereonto includes a signal level detection part detecting a level of a track error signal generated based on reflected light of the light beam from the disk recording medium, a scattered light detection part detecting scattering of the reflected light, and an off-track detection part which detects an off-track of the light beam using detection signals supplied from the signal level detection part and scattered light detection part.

Abstract: A disc player both translates and rotates a disc using a pair of parallel drive belts contacting opposed edges of a disc. Each drive belt spans a drive pulley and a passive driven pulley. The pulleys are supported on one of two sliding plates. The sliding plates are connected by a pair of pantograph-type rotatable mounting arms such that movement of one drive belt toward the disc forces the other drive belt to move an equal amount toward the disc. Each drive pulley is driven by a motor causing the drive belt to revolve. A spanning portion of each drive belt is urged against the edge of the disc, thereby establishing friction engagement between the belts and the disc such that the disc rotates when the belts rotate. A disc advance control system moves the disc linearly through an optical beam by differing the rotational frequency of one belt relative to the other. Disc advance may be accomplished with, or without, disc rotation.