| 摘要 |
<p>PURPOSE:To reset the display of a counter to ''0'' automatically, by providing a tape end detection circuit in which an output signal level is changed in detecting the tape end, and a means outputting a pulse with the change of the said signal level. CONSTITUTION:When the tape comes to its end at a time t1 and the rotation of a reel stand is stopped, since a pulse signal from a pulse generating circuit 101 is stopped, a capacitor 502 is not charged and not discharged at a resistor 502 immediately but gradually. Thus, the potential of the capacitor 502 is lowered gradually. When this potential is decreased to a value, the 1st one shot multivibrator circuit 504 is triggered to output a pulse having a prescribed pulse width. This pulse is inputted to the 2nd one shot mulivibrator 505. The 2nd one shot multivibrator 505 is triggered at the trailing of the pulse and outputs a signal of ''L'' level for a prescribed period. Thus, when the tape end is detected, the display of the counter is reset to ''0'' automatically.</p> |
