| 摘要 |
<p>PURPOSE:To improve reliability by eliminating malfunction, by carrying out magnetic tape end detection only with an open/close switch, resistor and capacitor in order to select properly the time factor of a charging and discharging circuit. CONSTITUTION:When a magnetic tape 13 reaches an end part, its tension change that moves an end detection tip 24 toward the direction indicated by an arrow mark 32 is generated to set an open/close switch 21 to be closed state. Since the switch 21 is connected to a charging and discharging circuit consisting of a resistor 29 and capacitor 30, the capacitor 30 in charged state performs discharging and changes the electric potential of the capacitor 30 accordingly. The waveform of the changed electric potential is shaped by a following chattering elimination circuit 26 and outputted to a motor controlling circuit 27 to stop or reversely rotates a motor. At this moment, the reliability can be improved extremely by setting the time factor RXC of the charging and discharging circuit consisting of the resistor 29 and capacitor 30 in the range of 50ms<=RC<=500ms.</p> |
