| 摘要 |
<p>PURPOSE:To secure reversing action of a tape, by avoiding detecting the lines of a magnetic tape part or the variable density of a magnetic matter if any and by detecting the leader tape part. CONSTITUTION:A magnetic tape 1 is driven toward an arrow 6 and reaches a leader tape part 1A, and the light emitted from a light emitting means 2 is reflected at the part 1A and fed to a photodetecting means 3. Thus the output of the means 3 has a drop of its level at the time t2. The output of the 1st integration circuit 8 has an attenuation in terms of exponent and function at and after the time t2 and is applied to a non-reverse input terminal 11a of an operational amplifier 11 and the 2nd integration cirlcuit 9. The output of the circuit 9 has a slower attenuation in terms of exponent and function and is applied to a reverse input terminal 11b of the amplifier 11. The amplifier 11 gives a command to a control part 12 to give the reverse travelling to the tape 1.</p> |
