OPTICAL DISK DEVICE, ESPECIALLY IN RELATION TO RECEIVING LIGHT BEAM ON AN INFORMATION SURFACE OF AN OPTICAL DISK

摘要

PURPOSE: An optical disk device is provided to reduce a speed of a focal point of light at the first acceleration, and to reduce at the second acceleration, in order to realize a focus jump into a desired information surface, thereby surely moving the focal point within a focus controllable range. CONSTITUTION: A light receiving portion(110) receives a light from a light source. A vertical moving portion(112) changes a position of the light receiving portion(110) into a direction vertical to an information surface of an optical disk(102), and moves a focal point of the light. A light receiver receives a reflected light of the information surface in plural areas, and generates plural signals. A signal generator generates a focus error signal based on the plural signals. A focus controller(116) generates a control signal based on the focus error signal. The control signal moves the focal point of the light up to a range where a focus control for the information surface is capable. The control signal reduces a speed of the focal point at the first acceleration while reducing at the second acceleration. An absolute value of the second acceleration is smaller than that of the first acceleration.