Optical disk drive with an accurately positioned objective lens

Claim 1

An optical disk apparatus, comprising: an optical head having means for converging a light beam along an axis onto an optical disk which includes tracks spaced from each other in a radial direction, the optical head also having means for detecting a light beam reflected by an optical disk and for detecting a light beam reflected by the optical disk and for outputting a detection signal; first driving means for moving the converging means of the optical head in a direction perpendicular to the axis of the light beam; second driving means for moving the optical head in the radial direction; means, responsive to the detection signal, for generating a tracking error signal which represents a tracking error with reference to a given track of the optical disk; means, responsive to the tracking error signal, for actuating the first driving means such that the converging means follows a track of the optical disk; means for constantly sensing the actual position of the converging means and for outputting a sensing signal corresponding to the actual position; means for producing a predetermined signal used for biasing the second driving means, the second driving means moving the optical head from a given track to a target track in response to the predetermined signal; means for storing a value of the sensing signal which the sensing means outputs before the optical head is moved from the given track to the target track while the converging means is in an initial position; means for stopping the track following movement of the converging means during an interval when the optical head is being moved from the given track to the target track; means for calculating the difference between the sensing signal value stored in the storing means and a value of the sensing signal which the sensing means outputs when the track following movement of the converging means has been stopped; means for holding the converging means at the initial position when the optical head is being moved from the given track to the target track in accordance with the difference calculated by the calculating means; and means for releasing the converging means from the holding means after the optical head is moved from the given track to the target track, to thereby resume the track following movement of the converging means.