| 摘要 |
<p>PURPOSE:To enhance the reliability of data by terminating the writing of the data only when results of the decision of the read data in both a writing direction and its opposite direction are good writing. CONSTITUTION:Input data to be recorded are supplied to an error correcting and coding circuit 11, their errors are corrected and they are coded, after that, they are supplied to a synchronizing signal adding circuit 12, a synchronizing signal to show the synchronizing lead-in pattern of a PLL for a data separator and the start of the data is added, its output is supplied to a modulating circuit 13 and it is written to an optical card 1 through an optical card. On the other hand, the signal read out of the optical card 1 is demodulated by a demodulating circuit 15 through a synchronization detecting circuit 14, its error is corrected by an error correcting circuit 16 and it is outputted. When a correction flag is generated by reading the written data in a forward direction or a reverse direction, the data are rewritten, and when an uncorrectable flag is not generated in both the directions, the writing of the data is terminated.</p> |
