VERFAHREN ZUM LESEN VON DATEN VON EINEM ROTIERENDEN PLATTENFOERMIGEN AUFZEICHNUNGSTRAEGER

摘要

When data is being read off a optical disc, the light beam can lose the data track if it encounters a dirty or damaged spot on the disc. A tracking circuit steers it back on to the correct track some distance after passing the dirty or damaged spot. In order that the light beam (L) is steered back on to the correct track (B) as soon as possible after passing a dirty spot (SK), the invention calls first for the address of the point (1) at which the light beam (L) leaves the track (B) to be stored. From the control signal necessary to bring the light beam back on to the correct track, a first modified control signal is then calculated and also stored. When, during subsequent plays, the light beam (L) comes to the point (1) on the disc, now stored in the memory, the first modified control signal is fed to the tracking circuit. In order to produce an optimum modified control signal, the light beam (L) is taken several times past the point (1) stored in the memory, and each time a new modified control signal is calculated and stored. The invention is of use in CD players, video disc players, DRAW disc players and magneto-optical recording and replaying devices.