Focus search method and controller for digital disk

Abstract

A focus search method and a controller for a digital disk overcomes a shortcoming of a conventional focus search method in which a focus search on a specified layer is always performed from the same direction if a layer jump for changing a layer has been improperly performed during reproduction from a digital disk such as a DVD having a plurality of recording layers, thus taking much time for the focus search when the focus search is begun from a point away from a specified layer. A focus direction used for an immediately preceding focus search performed from an initial focus search position at the outer side of two recording layers is stored in a focus direction memory of a focus direction setter. Based on the data stored in the memory and a signal indicating the position of a specified layer received from a layer specifier that instructs a layer jump, a setter for handling an improper focus jump makes settings so that a focus search is started from a side closer to the specified layer by performing a logical operation and a flow processing.