| 摘要 |
PURPOSE:To improve the detection precision with the simple constitution by averaging the induced potential of a pair of detection electrodes which induce the charged electricity on a thread, synchronously in a same phase, and operating a relay circuit by diffenentiation-amplifying each output signal. CONSTITUTION:When a thread 1 travels, the induction signal due to the commercial electric power and the detection signal corresponding to the electric charge on the thread are superposed onto the detection electrodes 2a and 2b, and applied onto terminals Pa and Pb. Since the induction signals are synchronized in a same phase, the signals are offset. While, since the detection signals are asynchronously induced in a same phase, the superposition signal of the both is generated in the output of a differential amplifier 5, and the output voltage R of a recitifier 6 becomes high potential. Therefore, the output signal of a comparator becomes zero, and a relay circuit 7 is input into into inoperative. When the traveling of the thread 1 stops because of cut, etc., the thread traveling signal induced in the direction electrode is eliminated, and the relay circuit 7 is put into operative, and the cut of thread is detected.
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