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 periodi c 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 m ay indicate whether or not the bottom of the pre-groove is closer to the scanni ng beam entry side of the disc. Further a scanning device is described comprisi ng a detector for detecting said phase based on the varying signal. The device adapts its scanning control means to the indicated property.