| 摘要 |
PURPOSE:To obtain the single shaped pulse in correspondence to the single detection pulse even though the noise waves are piled, by giving a waveform shaping to the detection pulse obtained from a piezoelectric sensor and through a Schmitt trigger circuit having a prescribed blind sector. CONSTITUTION:The electric signal, which is produced by applying the pressure signal to the piezoelectric sensor 1, is supplied to the reverse input terminal of the differential amplifier 17 constituting the Schmitt trigger circuit 4 and via an impedance converting circuit. When the electric signal received an impedance conversion becomes higher than the turn-on level V0, the output voltage of the amplifier 17 lowers down to the earth potential from a high level. Thus the diode 23 is turned on, and then the bias potential of the nonreverse input terminal lowers down to the turn-off level V1. When the above-mentioned electric signal becomes lower than the level V1, the output voltage turns to a high level again to turn off the diode 23. And the bias voltage of the nonreverse input terminal is reset to the level V0. |
