Abstract: An eccentricity amplitude of a medium in an eccentricity measuring unit and an eccentricity phase for a start position of one rotation are measured. A region from the start position to end position of one rotation of the medium which was measured is divided into a plurality of regions every predetermined rotational angle, addresses are sequentially allocated to those regions, a sine value of a rotational angle which is increased every predetermined rotational angle has been stored in each address in an eccentricity memory. A read control unit forms an address (a) in an eccentricity memory corresponding to a rotating position of the medium where a light beam is irradiated at present while using the start position of one rotation of the medium as a reference and reads out a corresponding sine value sin&thgr;a from the eccentricity memory by the designation of the address (a).

Abstract: An apparatus for suppressing warping of a rotating optical disk including a disk warp suppressing member facing a surface of the upturned side of the optical disk in a manner to be in sliding contact with the optical disk, and an elastic member for supporting the disk warp suppressing member and forcing it toward the optical disk. The apparatus also has a carriage which faces a rotation region of the optical disk so as to move freely in the radial direction of the optical disk, and is provided with light beam irradiating means, with the elastic member being fitted to the carriage.

Abstract: An optical storage apparatus has an eccentricity measuring unit that measures an eccentricity amplitude of a medium and an eccentricity phase for a start position along one rotation of a disk. A region from the start position to an end position of one rotation of the medium which was measured is divided into a plurality of regions every predetermined rotational angle, and addresses are sequentially allocated to those regions. A sine value of a rotational angle, which is increased every predetermined rotational angle, has been stored in each address in an eccentricity memory. A read control unit forms an address (a) in an eccentricity memory corresponding to a rotating position of the medium where a light beam is irradiated at present while using the start position of one rotation of the medium as a reference and reads out a corresponding sine value sin.theta.a from the eccentricity memory by the designation of the address (a).

Abstract: An optical disk device in which a moving state of a beam irradiating position is detected during the operation of an optical head in response to a jump signal, and in which an acceleration signal and a deceleration signal for said optical head are corrected based on a detection result for the subsequent jump operation, resulting in canceling an individual difference or the variation of the characteristic of the optical head.