Patent ID: 8199624

Claim:
An optical disc unit that records or reproduces data on and from an optical disc that has N number of recording layers (N is an integer equal to or larger than 3), comprising: an objective lens for focusing a laser light on the disc and positioning a focal point of laser light; error signal generating unit for generating a signal indicative of a focus error on the recording layers from a reflection light from the optical disc; drive unit for driving said objective lens in a direction perpendicular to the recording layers of the disc in accordance with the error signal; and correction unit for correcting the light intensity or light density at the focal point of the laser light that is generated by the objective lens, wherein: in the focal point position movement in which said drive unit drives said objective lens, and the focal point is moved from one recording layer to another based on the focus error signal that is detected by said error signal generation unit, when the focal point moves from one recording layer on which the laser light is focused to another layer that is not adjacent, and when the number of the recording layers to be passed through is one or more, said correction unit corrects the light intensity or light density at the focal point on the recording layer to be passed through.