Patent ID: 7187636

Claim:
A tilt correcting apparatus for correcting a tilt amount of a light beam to be radiated from a pickup to a disk, the apparatus comprising: a pre-pit signal producer configured to produce a pre-pit signal indicative of an existence/nonexistence of a pre-pit formed on the disk on the basis of returned light of the light beam radiated onto the disk; an RF signal producer configured to produced an RF signal from bits of information recorded on the disk on the basis of the returned light; a correcting-amount deciding unit configured to decide an optimum tilt-correcting amount by measuring an offset amount on the basis of a relationship between the pre-pit signal and the RF signal and making use of the measured offset amount; and a tilt corrector configured to correct the tilt amount on the basis of the optimum tilt-correcting amount, wherein the correcting-amount deciding unit comprises: a first detecting device configured to detect a first tilt amount providing an amount of the tilt maximizing the amplitude of the RE signal; a second detecting device configured to detect a second tilt amount providing an amount of the tilt maximizing an amplitude of the pre-pit signal; a calculating device configured to calculate an offset tilt amount indicative of a difference between the first and second tilt amounts; and a deciding device configured to decide the optimum tilt-correcting amount using the offset tilt amount.