UPPTECKNINGSBERARE, SAMT APPARAT FOR INSKRIVNING AV INFORMATION PA EN UPPTECKNINGSBERARE

摘要

A record carrier is described on which information is stored in an optically readable structure of trackwise arranged areas and intermediate areas. By giving the information tracks periodic excursions towards and away from adjacent tracks, in a direction transverse to the direction of reading, the period of the excursions being substantially greater than the average period of the areas and the amplitude of the excursions being smaller than the width of the tracks, a control signal for centering the read beam of radiation on an information track can be obtained without the use of additional optical means. The excursions of the tracks have such relative phase that the tracks are in nested concentric relation and one component of the stored information represents the phase of the undulations.