Patent ID: 6674694
Filing Date: 2004-01-06
Classification: G11B

Abstract:
A light-pickup device for an optical disk device which performs recording, reproduction or erasing of information of an optical disk having plural information recording layers, comprising:a light source; a lens for gathering light flux generated by said light source onto an image recording plane; a lens driver for driving said lens; a focus drive voltage controller for controlling a focus drive voltage applied to said lens driver, which kicks the focus drive voltage for accleration when the information recording layer is changed over, and kicks the focus drive voltage for deceleration when a focus zero cross is detected from a focus error signal detected based on reflected light flux from the information recording plane; an offset voltage controller which applies offset voltage to the focus error signal when the focus drive voltage controller is activated for changing over the information recording layer; a detection circuit which generates a focus zero cross signal by comparing the focus error signal having the offset voltage applied thereto against a reference level; and the offset voltage controller including: an operational amplifier having one input terminal to which the focus error signal is input, and another input terminal to which offset voltage is applied; a circuit means for changing over said offset voltage in response to a normal reproduction mode and a mode for changing the information recording layer; and, a controller for executing control for changing over sad circuit means.