The present invention generally relates to an optical disk and a recording/reproducing apparatus therefor, and particularly relates to a tracking system in the recording/reproducing apparatus.
A pre-groove is formed in a writable optical disk so that an information signal can be recorded efficiently on the optical disk by means of a light while the light beam tracks on the pre-groove. As a system of making a light beam perform tracking on a pre-groove formed in an optical disk, a far field system or a sample tracking servo system using wobbled pits has been conventionally used.
In the far field system, however, there has been a disadvantage in that an offset is sometimes generated in a tracking error signal. Further, in the sample tracking servo system, on the other hand, there has been a disadvantage in that a control circuit is complicated and a servo frequency band is limited (for example, Japanese Patent Post-examined Publication Nos. 59-18771 and 63-43812).