Patent ID: 7391684

Claim:
An optical disk recording/reproducing apparatus comprising: (1) an optical pickup that emits a laser beam containing main and sub beams onto an optical disk, the optical pickup including: main beam receiving means for receiving the main beam reflected from a target track of the optical disk; and sub beam receiving means for receiving the sub beam reflected from a position deviated from the target track; (2) a tracking error signal calculating circuit including: main push-pull signal generating means for generating a main push-pull signal which is a main servo error signal based on the main beam signal output from the main beam receiving means; sub push-pull signal generating means for generating a sub push-pull signal which is a sub servo error signal based on the sub beam signal output from the sub beam receiving means; amplifying means for amplifying the sub push-pull signal output from the sub push-pull signal generating means based on a gain value; and tracking error signal generating means for generating a differential-push-pull-scheme tracking error signal based on the main push-pull signal output from the main push-pull signal generating means and the sub push-pull signal output from the amplifying means; and (3) a processing section including: allowable gain-value range defining means for measuring the gain value corresponding to a level ratio between the main push-pull signal and the sub push-pull signal to define an allowable range of the gain value; eccentricity measuring means for measuring an eccentricity of the optical disk based on the sub push-pull signal; eccentricity determining means for determining whether or not the measured eccentricity is greater than or equal to a predetermined value; and gain-value defining means for defining a minimum value as a gain value of the amplifying means by selecting the minimum value of the gain value if the eccentricity is determined to be greater than or equal to the predetermined value and for defining a central value as a gain value of the amplifying means by selecting the central value of the gain value if the eccentricity is determined to be less than the predetermined value.