JPS6437701A - Positioning control system for magnetic tape device - Google Patents

Abstract

PURPOSE:To attain a correct positioning without erasing the trailing edge of a preceding block by returning a position to the preceding normal block already written for an overrun during a writing action, and writing the next block after checking a block number. CONSTITUTION:When an overrun detecting circuit 4 detects the overrun at a point A during the writing of an N-th block 20, a scanning control circuit 6 stops a capstan motor 12, turns on a reverse signal 17, and counts the number of the output pulses of an optical tachometer 13 from the point A through B, C and D to a point K with the aid of a tacho-pulse counting circuit 14 while returning the numbers. Next, the reverse signal is turned off at the point K, and the capstan motor 12 is stopped at a point L. Next, a forward signal 16 is turned on at the point L, a magnetic tape is shifted to the position of a point M, an N-1-th data block 21 is read out, and after confirming that the block number of this block is the N-1, the N-th block 20 is rewritten. Thus, the correct positioning can be executed.