Patent ID: 7852715
Filing Date: 2010-12-14
Classification: G11B

Abstract:
1. An optical disc apparatus configured to perform at least one of recording and reproducing different types of discs, the optical disc apparatus comprising: an optical pickup for irradiating the disc with laser light via an objective lens; an actuator for moving the objective lens in a focus direction; a focus detecting light receiving unit for detecting a focus state on the basis of reflected light from the disc; an FE signal measuring unit for measuring the amplitude of a focus error signal generated by the focus detecting light receiving unit; and a disc determining unit for storing a first threshold for determining the substrate thickness of the disc and a second threshold for determining the type of the disc and determining the type of the disc on the basis of the amplitude measured by the FE signal measuring unit, wherein: the disc determining unit deter mines the substrate thickness T of the disc on the basis of (FEmax−FEmin)/FSmax, where FEmax is a maximum value of the amplitude of the focus error signal, FEmin is a minimum value of the amplitude of the focus error signal, and FSmax is a maximum value of the amplitude of a focus sum signal, the disc determining unit determines that the disc is a Compact Disc based on the substrate thickness T being smaller than the first threshold, the disc determining unit determines that the disc has a non-Digital Versatile Disc surface of a dual disc having a Digital Versatile Disc surface and the non-Digital Versatile Disc surface based on the substrate thickness T being greater than the first threshold and smaller than a second threshold, the first threshold being smaller than the second threshold, and the disc determining unit determines that the disc is a Digital Versatile Disc having one layer based on the substrate thickness T being greater than the second threshold.