| 摘要 |
PURPOSE:To avoid a mistake where a defect of a recording medium is misunderstood as an address mark by forming an address mark with plural divided elements. CONSTITUTION:Plural FF circuits 2-20 form a shift register 1 which receives the read information B. Then outputs D0-D18 of the circuits 2-20 are supplied to an FF circuits 39 via AND circuits 21-24, NOR circuits 25-29, AND circuits 30-37 and an OR circuit 38 respectively. Then an address mark detecting signal H is delivered from the circuit 39. As a result, the address mark detecting signal is obtained from the output of another FF circuit even if the output of at least one of FF circuits is omitted. This can prevent a mistake where a defect of a recording medium is misunderstood as an address mark. |
