APPARATUS FOR READING A DISK-SHAPED RECORD CARRIER

摘要

19 "Apparatus for reading a disk-shaped record carrier" An optical read system for a disk-shaped record carrier. By means of a tracking system the read spot is centred at the information track. The control signal for this tracking system is obtained by means of additional radiation spots which are disposed on radially opposite sides of the read spot. By subjecting the detection signals corresponding to these additional radiation spots and the read spot to a special operation a control signal is obtained which is highly independent of variations in disk parameters, variations in the intensity of the radiation beams and focussing errors.