| 摘要 |
PURPOSE:To improve leakage of a current flowing to the resistance of a trigger circuit by connecting 1st to 3rd resistances in parallel and a transistor in series to a sensor circuit and by driving this transistor by the output of the sensor circuit. CONSTITUTION:To sensor circuit 1, the series circuit composed of resistances 25, 38 and 40 and transistor Tr24 is connected in parallel, and SCR22 is driven by circuit 1 via Tr24. When a detected object of metal, etc., approaches to detection coil 11, oscillation 12 stops and the output of [NC] is ''L'' at a normal time and ''H'' at a detection time. since Tr24 is OFF at the normal time and the threshold level of ZD35 is set smaller than that of constant-voltage diode ZD37, no current flows to resistances 25 and 38 and SCR22 turns OFF. At the detection time, Tr24 is ON and SCR is also ON; and a current is supplied to circuit 1 via resistances 38 and 25 and light emission diode 24 is also supplied with a current. Consequantly, no current flows through resistances 25 and 38 with SCR22 OFF, so that the leakage of a current will improve. |
