Patent ID: 7729221
Filing Date: 2010-06-01
Classification: G11B

Abstract:
1. An optical disk device, comprising: a laser unit including a first objective lens and a second objective lens, a numerical aperture of the first objective lens being different from a numerical aperture of the second objective lens; a first focus driver for detecting a first voltage value indicating the value of a driving voltage to drive the first objective lens when light beams are irradiated onto a surface of an optical disk via the first objective lens and a focus is achieved; a second focus driver for detecting a second voltage value indicating the value of a driving voltage to drive the second objective lens when light beams are irradiated onto the recording surface of said optical disk via the second objective lens and a focus is achieved; and a controller for discriminating the type of the optical disk, based on a difference between the first voltage value and the second voltage value, wherein: said controller discriminates the type of said optical disk as a DVD disk in case said difference is greater than a predetermined value and discriminates the type of said optical disk as a CD disk in case said difference is equal to or smaller than said predetermined value.