| 摘要 |
PURPOSE:To enable detection of a pulse signal having noise without distorsion in transmission of a control signal between exchanges by changing reference voltage to a high value automatically by a delay circuit. CONSTITUTION:When a signal of state (a) is impressed to an input terminal 11, if the input signal is lower than voltage Vth2, H level is outputted to an output terminal 17. When higher than voltage Vth2, the output terminal becomes L level. When output of the output terminal 17 changes from H level to L level, the signal of output 17 is inputted to an inversion amplifier 15 through a delay circuit 16, and input 18 changes from voltage Vth2 to Vth1. When the input signal changes from higher than voltage Vth1 to lower, output 17 changes from L level to H level. However, as the time t2 in which the input signal is lower than Vth1 is shorter than delay time td of the delay circuit 16, output and input 18 of the delay circuit 16 have no change. |
