| 摘要 |
<p>PURPOSE:To ensure an assured detection for the address mark even in case the spike-type error output may occur, by giving the rectification and integration to the reproduction output of the recording medium and then comparing such reproduction output with the reference voltage. CONSTITUTION:When reproduction output signal 15 is supplied to full-wave rectifier 20 from the recording medium, the full-wave rectification is carried out to reference level 16. Then output 25 is supplied to integrator 21, and integration output 26 is applied to comparator 22. The comparison is given at comparator 22 to reference level 27, and the comparison result is delivered. In this case, output 26 becomes lower than level 27 at the demagnetizing state region on the recording medium, and the comparison output features waveform 23. Accordingly, the address mark can be detected by measuring time length t0 of output 23.</p> |
