| 摘要 |
An apparatus is described for reading an optically readable record carrier in which a light beam which has been modulated by the record carrier is incident on a detector divided into four quadrants. A tracking-error signal is obtained by measuring the time intervals between corresponding zero crossings of a first signal supplied by two diagonally situated sub-detectors of said detector and a second signal supplied by the two other diagonally situated sub-detectors and/or all four sub-detectors. |
