GERAET ZUR WIEDERGABE VON DATEN.

摘要

The compact disc player has an optical read-out beam which is focussed onto the required data track via a focus regulation circuit and which is maintained in alignment with the data track via a track regulating circuit. The regulating amplifier (FR) is supplied with an offset compensation voltage which is varied until the level of the HF component of the focus error signal (FE) is a min. Pref. the data read-out beam is focussed onto four photodiodes (A,B,C,D) with a common voltage (UB) applied to their cathodes, their anodes connected in pairs to the positive and negative inputs of a difference amplifier (V) providing the focus error signal (FE). The latter is fed via a high-pass filter (HP), a rectifier (G) and an A/D converter to a microprocessor (MP) controlling the offset compensation voltage.