| 摘要 |
PURPOSE:To exactly judge the life of a magnetic head by counting the running length of a tape by means of cumulation of a forward rotation time of the capstan, and a time of converting a reverse rotation time according to the running speed ratio in the forward and reverse directions, to a forward rotation time. CONSTITUTION:Capstan motor driving command signals which are outputted by the forward direction lamp generator 2 and the reverse direction lamp generator 3 through the CPU1 are applied to the time counter driving circuit 8 through the summing amplifier 4. As a result, the circuit 8 multiplies a signal from the generator 3, whose polarity is different from that of the generator 2, by a multiple according to the forward and reverse running speed ratio, and converts a reverse direction running time to a forward direction running time. The time counter is controlled by this circuit 8, and the counter 7 counts a cumulative value of the forward direction running length of a tape and its reverse direction running length which has been converted to the forward direction. Accordingly, the actual running length of a tape can be grasped exactly. |
