Smooth Lock-In of Servo Control When Switched On

Smooth Lock-In of Servo Control When Switched On

An apparatus for playing optical discs is described, in which for a smoother locking-in of the focus servo control the focussing error signal is initially derived from the amplitude of the h.f. signal, followed by a gradual change-over to a difference signal derived by means of subdetectors. In this way the focus control point with the servo loop closed is shifted towards the desired in-focus point.

Patent :  US4683561 –  Smooth Lock-In of Servo Control When Switched On

Octrooi : NL8501509A – Inrichting voor het projecteren van een lichtbundel op een optisch uitleesbare registratiedrager.