| 摘要 |
PURPOSE:To perform signal transfer of high precision without using any photocoupler, etc., by composing a coupled circuits of a filter removing a noise by permitting an input or output signal to pass through it and a high impedance element occluding a mixing noise. CONSTITUTION:External circuit 40 is provided with battery 60 and input signal contacts 61-6N and coupled circuits 39A1-39AN are connected to respective signal contacts 61-6N. To those coupled circuits 39A1-39AN, high impedance element 71 is connected at earth-line common side 70 and coupled circuits 39A1-39AN are provided with filters 74 consisting of resistance 72 and capacitor 73. Further, high impedance circuit 75 is connected to filter 74. Then, high impedance element 71 occludes a noise mixing from common line 70 and through filters 74, only input signals depending upon the on-off operations of signal contacts 61-6N of external circuit 40 are transmitted to the input unit. Additionally, circuit 75 of an inverter circuit such as C-MOS stops a noise to be transmitted to the input unit. |
