| 摘要 |
<p>PURPOSE:To inexpensively manufacture a tape end detecting circuit and, at the same time, to accurately operate the circuit, by operating the shut-off plunger of a tape mechanism by the AND of the current level of a motor for capstan at the tape end and its differentiated output. CONSTITUTION:A motor current which increases at the tape end is differentiated at a differentiation circuit composed of C12, C13, R14, R15, D11, and Q12 and smoothed at a circuit composed of R18, R17, and C14, and then, the pulse thus obtained is amplified by a circuit composed of D12, Q13, and R18, expanded in width by a pulse width expanding circuit composed of D13, C15, R19-R22, and Q14, and inputted in D14 which is one terminal of an AND circuit. On the other hand, the output of R11, R12, R24, C11, and Q11 constituting a motor locking current detecting circuit is outputted as a signal when a motor is locked at the tape end and inputted in the other input terminal D15 of the AND circuit. A tape mechanism shut-off plunger is stably driven through a driving circuit composed of R23, Q16, and Q17 by means of the AND circuit composed of the D14, D15, and Q15 at the time of tape end.</p> |
