Regulating optical disk scanning during start=up phase of drive - using radial and tangential servo regulators responding to eliminate error between angles of optical scanner and that of disc

摘要

The optical disc system has a pick-up (A) coupled to, and controlled by, a processor (P) connected to a focus regulating circuit (FS), a radial servo regulator (KSX), a tangential servo regulator (KSY) and a tracking control servo (TS). Each stage connects to the pick-up unit via controlled switches (S1-S4). During start-up the focus unit responds to identify the correct position. At this point the tracking error signal is read and process to establish successive values for the tilt servo units (KSX,KSY) to eliminate any angular variation. USE/ADVANTAGE - Corrects for optical angular errors esp. in start-up phase where no data or modulation signals for evaluation are yet available. Can use already existing appts.