FOCUS REGULATION FOR AN APPARATUS FOR DISC-SHAPED ROTATING INFORMATION SUPPORTS

摘要

The focusing adjustment of a record player for rotary optical reading information supports (1) comprises an optical reader (4) which has a transducer-controlled focusing actuator (3). The loop gain of the regulation circuit is controlled by a control signal which, from the read HF-EFM-signal, influences in a plurality of steps the gain of the regulation circuit as a function of the type and the frequency of a disc faults which modify the controlling magnitude.