| 摘要 |
PURPOSE:To prevent the generation of malfunction or the like by sending a code signal being transmitted by communication to the detection circuit of the receiver, detecting the polarity inversion of the output of the detection circuit, and taking the output in a control microcomputer. CONSTITUTION:A receiver 12 is provided with a circuit consisting of a resistance, capacitor 23, and operation amplifier 24 as a circuit 21 detecting the output polarity inversion from a filter 20 followed by an LPF 20 at the poststage of a detection circuit 19. In this case, for example, a resistance 25 is set to be 1MOMEGA, resistance 22 to be 15MOMEGA, and the capacitor 23 to be 2200pF. The audio output is branched from the output of the detection circuit 19, which is connected to a speaker through an amplifier. Therefore, the output of the LPF 20 of a master unit 6 becomes the waveform producing fluctuation and rounding, when the AC current flows accross a resistance R and a capacitor C, the peak value of the waveform nearly coincides with the leading and trailing edges of the transmitted original waveform pulse, and the pulse width becomes the original value. |
