Patent ID: 7907501

Claim:
An optical disc apparatus comprising: an optical pickup unit having a semiconductor laser that radiates a laser light beam which is to be applied to an optical disc, a photo detector that has a plurality of light-receiving faces, which are disposed adjacent to each other, and each of which is disposed radially at an identical radial angle from a center of all of the plurality of light-receiving faces, and that, when the plurality of light-receiving faces receive a reflected light beam of the laser light beam applied to the optical disc, outputs photoelectric converted signals, each of which corresponds to a level of the reflected light beam at each of the plurality of light-receiving faces, a plurality of operational amplifiers that respectively output control signals for focus servo or track servo to the optical disc, based on the photoelectric converted signals, and an actuator that executes the focus servo or the track servo, based on the control signals; a driving unit that drives the actuator to execute the focus servo or the track servo, based on the control signals; a storage unit in which gain data is stored, the gain data being data for setting gains of the plurality of operational amplifiers; and a gain setting unit that adjusts gains of the plurality of operational amplifiers such that the gains have values equivalent to that the reflected light beam is evenly applied to the plurality of light-receiving faces, based on the gain data read from the storage unit, wherein initial gain data is stored in the storage unit, the initial gain data being data for setting initial gains of the plurality of operational amplifiers, and wherein the gain setting unit calculates gain data of the plurality of operational amplifiers such that gains of the plurality of operational amplifiers have values equivalent to that the reflected light beam is evenly applied to the plurality of light-receiving faces, based on the control signals obtained when the initial gains are set for the plurality of operational amplifiers, and wherein the gain setting unit calculates the gain data of the plurality of operational amplifiers when a difference between a DC value superimposed on the control signals and a reference DC value is equal to or larger than a predetermined value.