US Patent 7518967 Position control method and device, and optical disk device

A position control method is disclosed that is capable of precisely and stably controlling a position of an object lens relative to a recording medium. When controlling the position of the object lens in the tracking direction, first, an attempt is made to read address information recorded on the recording medium, and if the address information is not readable, the polarity of the tracking error signal used for servo control is reversed. As a result, even for a recording medium of a low quality or a nonstandard recording medium, which are treated as invalid media in the related art, it is possible to locate the object lens to the target position.