| 摘要 |
PURPOSE:To shorten the releasing time considerably, by connecting two diodes between two input terminals and the output terminal of a comparator to form a rapid discharge path for a capacitor. CONSTITUTION:When a switch 2 is turned on and a charge potential Vc of a capacitor 7 of a time constant circuit 3 is raised to exceed a voltage Vr of a reference voltage generating circuit 4 which is one input of an operational amplifier 5, an output Vo of the operational amplifier 5 becomes an L level, and the charge voltage Vc is discharged with a time constant determined by forward resistances of two diodes 21 and 22 and the capacitor 7. The reference voltage Vr is held higher than the L level by a voltage corresponding to the forward voltage drop of the diode 22, and the charge voltage Vc is held higher than the reference voltage Vr by a voltage corresponding to the forward voltage drop of the diode 21. When the switch 2 is turned off, the charge voltage Vc and the reference voltage Vr disappear in a high speed. Thus, the releasing time is shortened sufficiently. |
