| 摘要 |
PURPOSE:To eliminate the effect of the chattering phenomenon, by providing the light inserter on the transmission line of the output side of the photoswitch and then keeping the photosignal at a certain level for a time longer than the working time of the photoswitch. CONSTITUTION:Photoswitch 5 is driven by switching command given from transmitting unit 4 to be switched to the side of contacts a1 and a2 from the side of contacts b1 and b2. In such case, command 4a is supplied also to pulse generating circuit 6, and thus circuit 6 delivers the pulse of a certain duration. This pulse is applied to LED7, and photosignal 1e is delivered from LED7 for the time equivalent to the pulse duration to be then supplied to light inserter 8. Accordingly, the photosignal on optical transmission line 16 keeps a constant level as long as signal 1e is kept at a constant level and although output signal 1a has some chattering. Thus no chattering is caused. At the same time, the transmitting unit as the rear step which is connected via transmission line 16 incorporates error detecting circuit 9. And circuit 9 decides the output signal of photoelectric converter 2 as an error in case the output signal is kept as a constant level for more than a fixed time. |
