Optical record carrier and scanning device

摘要

An optical record carrier is described comprising a track for carrying data encoded in optical marks. A parameter of the track has a periodic variation for generating a varying signal when scanning the track, for example a variation of the center of a pre-groove usually called wobble. The track further comprises reference elements, e.g. headers, interrupting the periodic variation. The phase of the periodic variation after the reference elements is indicative of a property of the record carrier for controlling the scanning of the record carrier in dependence of said property. In particular the phase may indicate whether or not the bottom of the pre-groove is closer to the scanning beam entry side of the disc. Further a scanning device is described comprising a detector for detecting said phase based on the varying signal. The device adapts its scanning control means to the indicated property.