Signal detector for an optical information reproducing apparatus

摘要

Write data, which has been modulated in a 4/11 mode and converted in an NRZI mode, is written on a sample servo type optical disk by means of a magnetic head and a laser diode in a pickup. A signal reproducer in an optical disk unit comprises a differentiating circuit for differentiating a reproduced signal originating from data recorded on the optical disk after detected by the pickup, an A/D converter for sampling a differential signal synchronously with a channel clock, and a difference detector for reproducing data by performing difference detection on results of A/D conversion. The difference detector includes a register, a selector, and a determiner.