| 摘要 |
<p>PURPOSE:To realize not only a simple constitution but a low cost, by directly detecting the rotary pulse from a reel driving DC motor with brush. CONSTITUTION:A pulse-type part is detected for the current waveform of a reel driving DC motor M with brush. For this purpose, the change of voltage of a resistance R1 in a motor driving circuit 11 is applied to an input terminal 121 of a rotary pulse detecting circuit 12, and the output rectangular waveforms are integrated by an integral network 124 via a differential amplifying part 122 and mono- multi 123. This sawtooth wave output is applied to a switching circuit 125 to keep the circuit 25 off. When the motor M is stopped and a pulse-type part has disappeared in the current waveform, the output of the circuit 124 does not exist any more. Then an on-output given from the circuit 125 is applied to a logical circuit LC, and accordingly an automatic stopping action is performed via a control circuit. In such a way, the constitution is simplified with a low cost for an electronic tape counter.</p> |
